feat: Create a custom action to verify chart version

.github/actions/verify-chart-version/action.yml

@@ -0,0 +1,16 @@
+name: 'Verify Helm chart version bump'
+description: 'Checks if the Helm chart version number has been bumped'
+inputs:
+  chart:
+    description: 'Which chart to check'
+    required: true
+  base:
+    description: 'Ref to compare against'
+    required: false
+  token:
+    description: 'GitHub token'
+    default: '${{ github.token }}'
+    required: true
+runs:
+  using: 'node16'
+  main: 'dist/index.js'