Simplify if condition in build script

The of condition likely was wrongly inverted (it said it would run if the branch was _not_ master).
Also it's kinda useless anyway, as the trigger definitions above (in `on`) already restrict the branches.

.github/workflows/build-images.yml

@@ -31,13 +31,13 @@ jobs:
           install: true
       - name: Login to DockerHub
         uses: docker/login-action@v3
-        if: (github.ref != 'refs/heads/master' && github.event_name != 'pull_request') || github.event_name == 'schedule'
+        if: github.event_name != 'pull_request' || github.event_name == 'schedule'
         with:
           username: ${{ secrets.DOCKER_USERNAME }}
           password: ${{ secrets.DOCKER_PASSWORD }}
       - name: Login to GitHub Container Registry
         uses: docker/login-action@v3
-        if: (github.ref != 'refs/heads/master' && github.event_name != 'pull_request') || github.event_name == 'schedule'
+        if: github.event_name != 'pull_request' || github.event_name == 'schedule'
         with:
           registry: ghcr.io
           username: privatebin