Targets versioned Ubuntu.

.github/workflows/autofix.yaml

@@ -14,7 +14,7 @@ jobs:
 
   toc:
     name: Generator TOC and auto-commit
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - name: Install doctoc
         run: |
@@ -42,7 +42,7 @@ jobs:
 
   json:
     name: Format JSON files and create a PR
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - name: Install linter
@@ -69,7 +69,7 @@ jobs:
 
   typos:
     name: Fix typos and create a PR
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: sobolevn/misspell-fixer-action@0.1.0
@@ -90,7 +90,7 @@ jobs:
 
   images:
     name: Optimize images
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: calibreapp/image-actions@1.1.0

.github/workflows/autolock.yaml

@@ -9,7 +9,7 @@ name: Autolock
 
 jobs:
   lock:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: dessant/lock-threads@v2.0.1
         with:

.github/workflows/labels_sync.yaml

@@ -6,7 +6,7 @@ jobs:
 
   sync_labels:
     name: Sync labels
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: lannonbr/issue-label-manager-action@2.0.0

.github/workflows/lint.yaml

@@ -11,7 +11,7 @@ jobs:
 
   lint-markdown:
     name: Lint markdown
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: avto-dev/markdown-lint@v1.4.0
@@ -21,7 +21,7 @@ jobs:
 
   lint-awesome:
     name: Lint Awesome list
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
         with:
@@ -33,7 +33,7 @@ jobs:
 
   lint-yaml:
     name: Lint YAML files
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04
     steps:
       - uses: actions/checkout@v2.3.4
       - uses: actions/setup-python@v2.1.4