enable Maven cache

Author: Vladimir Kotal

.github/workflows/build.yml

@@ -13,6 +13,12 @@ jobs:
       uses: actions/setup-java@v1
       with:
         java-version: 11
+    - name: Cache Maven packages
+      uses: actions/cache@v2
+      with:
+        path: ~/.m2
+        key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+        restore-keys: ${{ runner.os }}-m2
     - name: Install pre-requisites
       run: ./dev/before_install
     - name: Before build actions
@@ -29,6 +35,12 @@ jobs:
       uses: actions/setup-java@v1
       with:
         java-version: 11
+    - name: Cache Maven packages
+      uses: actions/cache@v2
+      with:
+        path: ~/.m2
+        key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+        restore-keys: ${{ runner.os }}-m2
     - name: Install pre-requisites
       run: ./dev/before_install
     - name: Before build actions