adding github workflows

.github/workflows/changes.yaml

@@ -0,0 +1,28 @@
+name: Changes
+on:
+  workflow_call:
+    outputs:
+      api:
+        value: ${{ jobs.changes.outputs.api }}
+      app:
+        value: ${{ jobs.changes.outputs.app }}
+
+jobs:
+  changes:
+    name: filter
+    runs-on: ubuntu-latest
+    outputs:
+      api: ${{ steps.filter.outputs.api }}
+      app: ${{ steps.filter.outputs.app }}
+    steps:
+      - uses: actions/checkout@v3
+      
+      - uses: dorny/paths-filter@v3
+        id: filter
+        with:
+          initial-fetch-depth: 2
+          filters: |
+            api:
+              - 'api/**'
+            app:
+              - 'app/**'