Cache maven artifacts used by IntelliJ build (#27)

Co-authored-by: Sonakshi Saxena <nexa@google.com>

.github/workflows/build.yml

@@ -17,6 +17,12 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v3
 
+      - name: Cache local Maven repository
+        uses: actions/cache@v3.0.2
+        with:
+          path: ~/.m2/repository
+          key: ${{ runner.os }}-maven-${{ hashFiles('build.txt') }}
+
       - name: Set up JDK 17
         uses: actions/setup-java@v3
         with: