Update gradle wrapper and workflow jdk

Author: Player3324

.github/workflows/build.yml

@@ -4,7 +4,7 @@ jobs:
   build:
     strategy:
       matrix:
-        java: [8-jdk, 11-jdk, 15-jdk]
+        java: [8-jdk, 11-jdk, 16-jdk]
     runs-on: ubuntu-20.04
     container:
       image: openjdk:${{ matrix.java }}
@@ -13,4 +13,4 @@ jobs:
       - uses: actions/checkout@v1
       - uses: gradle/wrapper-validation-action@v1
       - run: chmod +x ./gradlew
-      - run: ./gradlew build test --stacktrace
+      - run: ./gradlew build test --stacktrace

.github/workflows/release.yml

@@ -4,7 +4,7 @@ jobs:
   build:
     runs-on: ubuntu-20.04
     container:
-      image: openjdk:15-jdk
+      image: openjdk:16-jdk
       options: --user root
     steps:
       - uses: actions/checkout@v1

gradle/wrapper/gradle-wrapper.properties

@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.7.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.0-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists