fix ansible-lint yaml nitpicks

- rules-warning.yml: remove trailing blank line
- pr-test.yml: quote 'on' key for yaml truthy, add newline at EOF
- add .yamllint config to ignore SOPS-encrypted secrets (line-length unfixable without re-encrypting)

ansible/.yamllint

@@ -0,0 +1,11 @@
+---
+extends: default
+
+rules:
+  line-length:
+    max: 160
+  truthy:
+    allowed-values: ["true", "false"]
+
+ignore:
+  - group_vars/all/secrets.enc.yaml

ansible/dotfiles/pr-test.yml

@@ -1,6 +1,6 @@
 name: PR Test
 
-on:
+"on":
   pull_request:
     branches:
       - master
@@ -27,4 +27,4 @@ jobs:
 
       - name: Only build
         run: |
-          docker buildx build --platform linux/amd64 --output "type=image,push=false" -f tests/Dockerfile-${{ matrix.distro }} .
+          docker buildx build --platform linux/amd64 --output "type=image,push=false" -f tests/Dockerfile-${{ matrix.distro }} .

ansible/services/grafana/provisioning/alerting/rules-warning.yml

@@ -239,4 +239,3 @@ groups:
         labels:
           severity: warning
         isPaused: false
-