bump required go version to 1.17 (#5107)

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

go.mod

 module github.com/coredns/coredns
 
-go 1.16
+go 1.17
 
 require (
 	github.com/Azure/azure-sdk-for-go v61.1.0+incompatible
 	github.com/Azure/go-autorest/autorest v0.11.24
 	github.com/Azure/go-autorest/autorest/azure/auth v0.5.11
-	github.com/Azure/go-autorest/autorest/to v0.2.0 // indirect
 	github.com/apparentlymart/go-cidr v1.1.0
 	github.com/aws/aws-sdk-go v1.42.35
 	github.com/coredns/caddy v1.1.1
@@ -14,7 +13,6 @@ require (
 	github.com/farsightsec/golang-framestream v0.3.0
 	github.com/golang/protobuf v1.5.2
 	github.com/grpc-ecosystem/grpc-opentracing v0.0.0-20180507213350-8e809c8a8645
-	github.com/imdario/mergo v0.3.12 // indirect
 	github.com/infobloxopen/go-trees v0.0.0-20200715205103-96a057b8dfb9
 	github.com/matttproud/golang_protobuf_extensions v1.0.1
 	github.com/miekg/dns v1.1.45
@@ -25,7 +23,6 @@ require (
 	github.com/prometheus/client_golang v1.11.0
 	github.com/prometheus/client_model v0.2.0
 	github.com/prometheus/common v0.32.1
-	github.com/stretchr/objx v0.2.0 // indirect
 	go.etcd.io/etcd/api/v3 v3.5.1
 	go.etcd.io/etcd/client/v3 v3.5.1
 	golang.org/x/crypto v0.0.0-20211215153901-e495a2d5b3d3
@@ -38,3 +35,79 @@ require (
 	k8s.io/client-go v0.23.1
 	k8s.io/klog/v2 v2.40.1
 )
+
+require (
+	cloud.google.com/go/compute v0.1.0 // indirect
+	github.com/Azure/go-autorest v14.2.0+incompatible // indirect
+	github.com/Azure/go-autorest/autorest/adal v0.9.18 // indirect
+	github.com/Azure/go-autorest/autorest/azure/cli v0.4.5 // indirect
+	github.com/Azure/go-autorest/autorest/date v0.3.0 // indirect
+	github.com/Azure/go-autorest/autorest/to v0.2.0 // indirect
+	github.com/Azure/go-autorest/logger v0.2.1 // indirect
+	github.com/Azure/go-autorest/tracing v0.6.0 // indirect
+	github.com/DataDog/datadog-agent/pkg/obfuscate v0.0.0-20211129110424-6491aa3bf583 // indirect
+	github.com/DataDog/datadog-go v4.8.2+incompatible // indirect
+	github.com/DataDog/datadog-go/v5 v5.0.2 // indirect
+	github.com/DataDog/sketches-go v1.0.0 // indirect
+	github.com/Microsoft/go-winio v0.5.1 // indirect
+	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/cespare/xxhash/v2 v2.1.1 // indirect
+	github.com/coreos/go-semver v0.3.0 // indirect
+	github.com/coreos/go-systemd/v22 v22.3.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/dgraph-io/ristretto v0.1.0 // indirect
+	github.com/dimchansky/utfbom v1.1.1 // indirect
+	github.com/dustin/go-humanize v1.0.0 // indirect
+	github.com/evanphx/json-patch v4.12.0+incompatible // indirect
+	github.com/flynn/go-shlex v0.0.0-20150515145356-3f9db97f8568 // indirect
+	github.com/go-logr/logr v1.2.0 // indirect
+	github.com/gogo/protobuf v1.3.2 // indirect
+	github.com/golang-jwt/jwt/v4 v4.2.0 // indirect
+	github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b // indirect
+	github.com/golang/groupcache v0.0.0-20210331224755-41bb18bfe9da // indirect
+	github.com/google/go-cmp v0.5.6 // indirect
+	github.com/google/gofuzz v1.2.0 // indirect
+	github.com/google/uuid v1.3.0 // indirect
+	github.com/googleapis/gax-go/v2 v2.1.1 // indirect
+	github.com/googleapis/gnostic v0.5.5 // indirect
+	github.com/imdario/mergo v0.3.12 // indirect
+	github.com/jmespath/go-jmespath v0.4.0 // indirect
+	github.com/josharian/intern v1.0.0 // indirect
+	github.com/json-iterator/go v1.1.12 // indirect
+	github.com/mailru/easyjson v0.7.7 // indirect
+	github.com/mitchellh/go-homedir v1.1.0 // indirect
+	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
+	github.com/modern-go/reflect2 v1.0.2 // indirect
+	github.com/opentracing-contrib/go-observer v0.0.0-20170622124052-a52f23424492 // indirect
+	github.com/oschwald/maxminddb-golang v1.8.0 // indirect
+	github.com/philhofer/fwd v1.1.1 // indirect
+	github.com/pkg/errors v0.9.1 // indirect
+	github.com/prometheus/procfs v0.6.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+	github.com/stretchr/objx v0.2.0 // indirect
+	github.com/tinylib/msgp v1.1.2 // indirect
+	go.etcd.io/etcd/client/pkg/v3 v3.5.1 // indirect
+	go.opencensus.io v0.23.0 // indirect
+	go.uber.org/atomic v1.7.0 // indirect
+	go.uber.org/multierr v1.6.0 // indirect
+	go.uber.org/zap v1.17.0 // indirect
+	golang.org/x/mod v0.4.2 // indirect
+	golang.org/x/net v0.0.0-20211216030914-fe4d6282115f // indirect
+	golang.org/x/oauth2 v0.0.0-20211104180415-d3ed0bb246c8 // indirect
+	golang.org/x/term v0.0.0-20210615171337-6886f2dfbf5b // indirect
+	golang.org/x/text v0.3.7 // indirect
+	golang.org/x/time v0.0.0-20211116232009-f0f3c7e86c11 // indirect
+	golang.org/x/tools v0.1.6-0.20210726203631-07bc1bf47fb2 // indirect
+	golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 // indirect
+	google.golang.org/appengine v1.6.7 // indirect
+	google.golang.org/genproto v0.0.0-20220107163113-42d7afdf6368 // indirect
+	google.golang.org/protobuf v1.27.1 // indirect
+	gopkg.in/inf.v0 v0.9.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
+	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
+	k8s.io/kube-openapi v0.0.0-20211115234752-e816edb12b65 // indirect
+	k8s.io/utils v0.0.0-20210930125809-cb0fa318a74b // indirect
+	sigs.k8s.io/json v0.0.0-20211020170558-c049b76a60c6 // indirect
+	sigs.k8s.io/structured-merge-diff/v4 v4.1.2 // indirect
+	sigs.k8s.io/yaml v1.2.0 // indirect
+)