Adds curlylint workflow

.github/workflows/curlylint.yaml

@@ -0,0 +1,28 @@
+name: Templates validator
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Install curlylint
+        run: pip install curlylint
+
+      - name: Run linter
+        run: >
+          curlylint --rule 'aria_role: true' \
+           --rule 'django_forms_rendering: true' \
+           --rule 'html_has_lang: true' \
+           --rule 'image_alt: true' \
+           --rule 'meta_viewport: true' \
+           --rule 'no_autofocus: true' \
+           --rule 'tabindex_no_positive: true' \
+           --exclude '_modal.html|create_status/layout.html' \
+          bookwyrm/templates