remove old build yml

.github/workflows/gradle_build.yml

@@ -1,16 +0,0 @@
-name: Build
-
-on: [push]
-
-jobs:
-  build:
-    runs-on: ubuntu-latest
-
-    steps:
-      - uses: actions/checkout@v2
-      - name: Set up JDK 1.8
-        uses: actions/setup-java@v1
-        with:
-          java-version: 1.8
-      - name: Build with Gradle
-        run: ./gradlew build