don't run the build workflow in a cron job (#14)

* don't run the build workflow in a cron job

This means we won't get the most recent Chrome version, but at least we don't
regularly break the Chrome interop image.

* simplify ifs

.github/workflows/build.yml

@@ -4,8 +4,6 @@ on:
     branches: [ master ]
   pull_request:
     branches: [ master ]
-  schedule:
-    - cron: '0 0 * * *'
 
 jobs:
   build:
@@ -14,12 +12,12 @@ jobs:
       - uses: actions/checkout@v4
       - name: Login to Docker Hub
         uses: docker/login-action@v3
-        if: ${{ github.event_name != 'pull_request' }}
+        if: ${{ github.event_name == 'push' }}
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
       - name: Build endpoint
         uses: docker/build-push-action@v5
         with:
-          push: ${{ github.event_name != 'pull_request' }}
+          push: ${{ github.event_name == 'push' }}
           tags: martenseemann/chrome-quic-interop-runner:latest