Add changelog workflow

.github/changelog.sh

@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+m_branch=m;
+changelog_file=CHANGELOG.md;
+
+# fetch master since we might be in a shallow clone
+git fetch origin "$m_branch:$m_branch" --depth=1
+
+changed=0;
+for log in */"$changelog_file"; do
+    dir=$(dirname "$log");
+    # check if version changed
+    if git diff "$m_branch" -- "$dir/Cargo.toml" | grep -q "^-version = "; then
+        # check if changelog updated
+        if git diff --exit-code --no-patch "$m_branch" -- "$log"; then
+            echo "$dir version changed, but $log is not updated"
+            changed=1;
+        fi
+    fi
+done
+
+exit "$changed";

.github/workflows/rust.yml

@@ -67,3 +67,9 @@ jobs:
         cache-on-failure: "true"
     - name: Run clippy
       run: cargo clippy --all-features -- -D clippy::all
+  check-changelog:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - name: Check changelogs
+      run: ./.github/changelog.sh