Try container, but it will probably fail

.gitea/workflows/lint.yaml

@@ -0,0 +1,19 @@
+name: Linting
+
+on:
+  pull_request:
+
+jobs:
+  lint:
+    runs-on: cth-ubuntu-latest
+    container:
+      image: docker.atomaka.com/mdformat
+    steps:
+      - run: mdformat --check _posts/
+  build:
+    runs-on: cth-ubuntu-latest
+    steps:
+      - run: |
+          gem install bundler
+          bundle install
+          bundle exec jekyll build