Improve workflows

.github/workflows/flake-update.yaml

@@ -1,11 +1,11 @@
+---
 name: Periodic flake update
-on:
+on:  # yamllint disable-line rule:truthy
   schedule:
-    - cron: '0 */2 * * *'
-  workflow_dispatch:
+    - cron: "0 */2 * * *"
 
-  permissions:
-    contents: write
+permissions:
+  contents: write
 
 jobs:
   flake-update:
@@ -23,4 +23,3 @@ jobs:
         run: nix flake update --commit-lock-file
       - name: push
         run: git push
-