Cache examples in Github workflow

.github/workflows/build.yml

@@ -27,6 +27,12 @@ jobs:
       - name: Install dependencies
         run: npm install
 
+      - name: Cache examples
+        uses: actions/cache@v3
+        with:
+          path: examples
+          key: ${{ hashFiles('script/parse-examples') }}
+
       - name: Test corpus & parse examples
         run: npm test