CI: combine the qa and build stage into a single workflow

This does not have any immediate benefits but allows us to add a publish
stage in the next step that depends on all the qa steps to complete
successfully and use the artifacts generated by the build stage.

Signed-off-by: Leonard Göhrs <l.goehrs@pengutronix.de>

.github/workflows/qa.yaml → .github/workflows/check-and-build.yaml

@@ -1,4 +1,4 @@
-name: Quality Assurance
+name: Check and Build
 
 on: [push, pull_request]
 
@@ -26,3 +26,17 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - run: make qa-ruff
+
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # include tags and full history for setuptools_scm
+          fetch-depth: 0
+      - run: make build
+      - uses: actions/upload-artifact@v4
+        with:
+          name: dist
+          path: dist