CI: build source distribution and wheel

This is mostly to check that the respective make target stil works,
but maybe the generated wheels can also come in handy.

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

.github/workflows/build.yaml

@@ -0,0 +1,14 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: Source Distribution and Wheel
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - run: make build
+      - uses: actions/upload-artifact@v4
+        with:
+          path: dist