add detect-changed-manifests script

ci/detect-changed-manifests.sh

@@ -0,0 +1,25 @@
+# Source this file.
+#
+# Detects any manifests whose versions have changed.
+# Does so by comparing the current version in the Cargo.toml with the previous
+# version in the last commit. Intended for squash-merged PRs.
+
+detect_changed_manifests() {
+  local changed_manifests=()
+  local cargo_toml_files=$(find . -name "Cargo.toml")
+
+  for file in $cargo_toml_files; do
+    # Get the current version from the manifest.
+    local current_version=$(grep -E '^version\s*=' "$file" | sed -E 's/version\s*=\s*"(.*)"/\1/')
+
+    # Get the previous version from the last commit.
+    local previous_version=$(git show HEAD~1:"$file" | grep -E '^version\s*=' | sed -E 's/version\s*=\s*"(.*)"/\1/' 2>/dev/null)
+
+    # Compare the versions and add the path to the list if they are different.
+    if [ "$current_version" != "$previous_version" ]; then
+      changed_manifests+=("$file")
+    fi
+  done
+
+  echo "${changed_manifests[@]}"
+}