chore: Update CI workflow to only trigger on push to the main branch

.gitea/workflows/ci.yaml

@@ -1,8 +1,10 @@
 name: CI
 
 on:
-  - push
-  - pull_request
+  push:
+    branches:
+      - main
+  pull_request:
 
 jobs:
   cache-and-install:
@@ -22,7 +24,7 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: 20
-          cache: "pnpm"
+          cache: 'pnpm'
 
       - name: Install dependencies
         run: pnpm install # --frozen-lockfile