Makefile.release: do a complete dry-run (#4488)

Just dry-run all important targets.
Signed-off-by: Miek Gieben <miek@miek.nl>

.github/workflows/go.test.yml

@@ -79,4 +79,4 @@ jobs:
       uses: actions/checkout@v2
 
     - name: Test Makefile
-      run: make -f Makefile.release build
+      run:  make DOCKER=bla GITHUB_ACCESS_TOKEN=bla -n build docker github-push docker-push -f Makefile.release