Add cache to gradle

.github/workflows/tests.yml

@@ -19,6 +19,16 @@ jobs:
         java-version: 1.11
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
+    - name: Setup gradle cache
+      uses: burrunan/gradle-cache-action@v1
+      with:
+        save-generated-gradle-jars: false
+        save-local-build-cache: false
+        save-gradle-dependencies-cache: true
+        save-maven-dependencies-cache: true
+        # Ignore some of the paths when caching Maven Local repository
+        maven-local-ignore-paths: |
+          net/minestom/
     - name: Build Minestom
       run: ./gradlew build
     - name: Run tests