Run CI on pull requests + Test packaging

.github/workflows/ci.yml

@@ -1,6 +1,6 @@
 name: CI
 
-on: push
+on: [push, pull_request]
 
 jobs:
   lint:
@@ -22,6 +22,8 @@ jobs:
         run: pnpm install --frozen-lockfile
       - name: Run build
         run: VITE_API_URL="https://staging-api.modrinth.com/v2/" pnpm build
+      - name: Run package
+        run: pnpm package
       - name: Run lint
         run: pnpm lint
       - name: Run check