Merge remote-tracking branch 'upstream/master' into pr/391

.gitattributes

@@ -0,0 +1,3 @@
+# Don't export certain files via `git archive` (e.g. via "Download ZIP")
+.gitattributes export-ignore
+.github export-ignore

.github/workflows/ci.yml

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+name: Check
+
+on:
+  push:
+    branches:
+      - master
+      - releases/v[0-9]+.[0-9]+.[0-9]+
+  pull_request:
+    types: [opened, synchronize]
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  validate_copyright:
+    name: Copyright
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+      with:
+        show-progress: false
+    - name: Validate copyright file with debian-control-linter
+      uses: tibetiroka/debian-control-linter-action@v1
+      with:
+        type: 'debian/copyright'
+        file: 'copyright'
+        preset: 'strict'
+        enable: 'trailingSpace,upstreamContactStyle,urlForceHttps,fieldNameCapitalization,maintainerNameFullStop,urlExists,copyrightSourceStyle'