Merge cross-rs#552

552: Add changelog.yml GHA workflow r=adamgreig a=therealprof

Adds a GHA check to ensure every PR is accompanied by a edit of CHANGELOG.md to list the changes so we don't run into the usual issue of having to come up with all entries when someone requests a release.

Co-authored-by: Daniel Egger <daniel@eggers-club.de>

.github/workflows/changelog.yml

@@ -0,0 +1,19 @@
+on:
+  pull_request:
+
+name: Changelog check
+
+jobs:
+  changelog:
+    name: Changelog check
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v2
+
+      - name: Changelog updated
+        uses: Zomzog/changelog-checker@v1.1.0
+        with:
+          fileName: CHANGELOG.md
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}