ci: run docker builds from PRs

This way we can test if we break the build process from a PR.

Author: potyl

.github/workflows/pull-request.yaml

@@ -0,0 +1,21 @@
+name: Pull Request
+
+on:
+  pull_request:
+
+# Cancel existing workflows running for this PR
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
+defaults:
+  run:
+    shell: bash
+
+jobs:
+  docker-build:
+    name: Docker Build
+    uses: ./.github/workflows/docker-build.yaml
+    secrets: inherit
+    with:
+      push: false