Add yamllint (#26965)

So that https://github.com/go-gitea/gitea/pull/26964 does not happen
again. Merge this after that PR. Config is based on
[node's](https://github.com/nodejs/node/blob/main/.yamllint.yaml).

---------

Co-authored-by: techknowlogick <techknowlogick@gitea.com>

.github/workflows/files-changed.yml

@@ -17,6 +17,8 @@ on:
         value: ${{ jobs.detect.outputs.docker }}
       swagger:
         value: ${{ jobs.detect.outputs.swagger }}
+      yaml:
+        value: ${{ jobs.detect.outputs.yaml }}
 
 jobs:
   detect:
@@ -30,6 +32,7 @@ jobs:
       templates: ${{ steps.changes.outputs.templates }}
       docker: ${{ steps.changes.outputs.docker }}
       swagger: ${{ steps.changes.outputs.swagger }}
+      yaml: ${{ steps.changes.outputs.yaml }}
     steps:
       - uses: actions/checkout@v3
       - uses: dorny/paths-filter@v2
@@ -82,3 +85,8 @@ jobs:
               - "package.json"
               - "package-lock.json"
               - ".spectral.yaml"
+
+            yaml:
+              - "**/*.yml"
+              - "**/*.yaml"
+              - ".yamllint.yaml"

.github/workflows/pull-compliance.yml

@@ -39,6 +39,19 @@ jobs:
       - run: make deps-py
       - run: make lint-templates
 
+  lint-yaml:
+    if: needs.files-changed.outputs.yaml == 'true'
+    needs: files-changed
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-python@v4
+        with:
+          python-version: "3.11"
+      - run: pip install poetry
+      - run: make deps-py
+      - run: make lint-yaml
+
   lint-swagger:
     if: needs.files-changed.outputs.swagger == 'true'
     needs: files-changed

.github/workflows/pull-db-tests.yml

@@ -88,7 +88,7 @@ jobs:
       mysql:
         image: mysql:5.7
         env:
-          MYSQL_ALLOW_EMPTY_PASSWORD: yes
+          MYSQL_ALLOW_EMPTY_PASSWORD: true
           MYSQL_DATABASE: test
         ports:
           - "3306:3306"
@@ -160,7 +160,7 @@ jobs:
       mysql:
         image: mysql:5.7
         env:
-          MYSQL_ALLOW_EMPTY_PASSWORD: yes
+          MYSQL_ALLOW_EMPTY_PASSWORD: true
           MYSQL_DATABASE: test
         ports:
           - "3306:3306"
@@ -205,7 +205,7 @@ jobs:
       mysql8:
         image: mysql:8
         env:
-          MYSQL_ALLOW_EMPTY_PASSWORD: yes
+          MYSQL_ALLOW_EMPTY_PASSWORD: true
           MYSQL_DATABASE: testgitea
         ports:
           - "3306:3306"