Add yamllint (#321)

Reviewed-on: https://codeberg.org/Codeberg/pages-server/pulls/321
Reviewed-by: crapStone <codeberg@crapstone.dev>
Co-authored-by: pat-s <patrick.schratz@gmail.com>
Co-committed-by: pat-s <patrick.schratz@gmail.com>

.woodpecker/lint.yml

@@ -25,6 +25,16 @@ steps:
       - event: push
         branch: renovate/*
 
+  yamllint:
+    image: pipelinecomponents/yamllint:0.31.1
+    depends_on: []
+    commands:
+      - yamllint .
+    when:
+      - event: pull_request
+      - event: push
+        branch: renovate/*
+
   prettier:
     image: docker.io/woodpeckerci/plugin-prettier:0.1.0
     depends_on: []