fix install

ansible/install.yaml

@@ -15,22 +15,6 @@
         - git-registry.mycard.moe/nanahira/docker-ocserv
         - git-registry.mycard.moe/railgun/openconnect
       when: not noBird
-    - name: unstable source
-      become: true
-      copy:
-        content: | 
-          deb http://mirrors.tuna.tsinghua.edu.cn/debian unstable main contrib non-free
-        dest: /etc/apt/sources.list.d/unstable.list
-      when: systemBird and ansible_distribution == 'Debian' and ansible_distribution_release != 'sid'
-    - name: unstable pref 90
-      become: true
-      copy:
-        content: | 
-          Package: *
-          Pin: release a=unstable
-          Pin-Priority: 90
-        dest: /etc/apt/preferences.d/limit-unstable
-      when: systemBird and ansible_distribution == 'Debian' and ansible_distribution_release != 'sid'
     - name: netcat-openbsd
       become: true
       apt: