Define github CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,50 @@
+name: ci
+
+on:
+  # Triggers the workflow on push or pull request events but only for the main branch
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+  # Allows you to run this workflow manually from the Actions tab
+  workflow_dispatch:
+
+jobs:
+  install:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/cache@v3
+        with:
+          path: |
+            **/node_modules
+            .yarn/cache
+          key: ${{ runner.os }}-yarn-cache-${{ hashFiles('./yarn.lock') }}
+
+      - name: yarn-install
+        # Check out the lockfile from main, reinstall, and then
+        # verify the lockfile matches what was committed.
+        run: |
+            yarn install --immutable
+            CHANGES=$(git status -s)
+            if [[ ! -z $CHANGES ]]; then
+              echo "Changes found: $CHANGES"
+              git diff
+              exit 1
+            fi
+
+  validate:
+    runs-on: ubuntu-latest
+    needs: [install]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/cache@v3
+        with:
+          path: |
+            **/node_modules
+            .yarn/cache
+          key: ${{ runner.os }}-yarn-cache-${{ hashFiles('./yarn.lock') }}
+
+      - name: cgp-validation
+        run: yarn run validate