update github action to the new setup

.github/workflows/build.yml

@@ -26,14 +26,14 @@ jobs:
               uses: actions/cache@v2
               with:
                   path: |
-                      ~/.m2/repository/
-                      work/Minecraft
-                  key: ${{ runner.os }}-paper-2-${{ hashFiles('**/pom.xml') }}
+                    ~/.gradle/caches
+                    ~/.gradle/jdks
+                    ~/.gradle/native
+                    ~/.gradle/wrapper
+                  key: ${{ runner.os }}-paper-2-${{ hashFiles('**/*.gradle*', 'gradle/**', 'gradle.properties') }}
                   restore-keys: ${{ runner.os }}-paper-2
             - name: Patch and build
               run: |
                   git config --global user.email "no-reply@github.com"
                   git config --global user.name "Github Actions"
-                  ./paper build
-            - name: Build javadocs
-              run: mvn -pl Paper-API,Paper-MojangAPI -am javadoc:javadoc
+                  ./gradlew applyPatches build