ci: Continuously build the PySide6 package

Add a CI job that does the following:

1. Continuously build the package, and upload it in the workflow
   pipeline.
2. Check that the version that we package does not lag behind the PyPI
   one.

.github/workflows/ci.yml

@@ -0,0 +1,47 @@
+name: PySide6 CI
+on:
+  push:
+  pull_request:
+    branches: [ main ]
+  schedule:
+    - cron: '0 0 * * *' # Run every day at 00:00 UTC.
+
+jobs:
+  build-package:
+    name: "Build the PySide6 package for Fedora ${{matrix.version}}"
+    runs-on: ubuntu-latest
+    container: fedora:${{ matrix.version }}
+    strategy:
+      matrix:
+        include:
+          - version: "38"
+          - version: "39"
+    env:
+      rpm_name: python3-pyside6-6.6.1-1.fc${{matrix.version}}.x86_64.rpm
+      srpm_name: python3-pyside6-6.6.1-1.fc${{matrix.version}}.src.rpm
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install build dependencies
+        run: sudo dnf install -y rpm-build python3-devel
+      - name: Build the PySide6 package
+        run: ./build.sh
+      - name: Upload binary RPM
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ env.rpm_name }}
+          path: "./rpmbuild/RPMS/x86_64/${{ env.rpm_name }}"
+      - name: Upload source RPM
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ env.srpm_name }}
+          path: "./rpmbuild/SRPMS/${{ env.rpm_name }}"
+
+  check-updates:
+    name: "Ensure our package does not lag behind the PyPI one"
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Install dependencies
+        run: sudo apt-get install -y python-requests
+      - name: Check if there is a PySide6 update
+        run: ./check_updates.py