Update build scripts for Gradle 7 (#247)

* fabric: Update Loom to 0.7-SNAPSHOT

* Update to Gradle 7

Switch to CadixDev/licenser
The plugin we were using before does not support Gradle 7, and hasn't been updated in over a year.

* Remove `jcenter()` references

* Move to new JDA repo and bump version

* Use setup-java v2 and Adopt JDK 16 in gh actions

* build: Temporarily add Incendo repo for plugin resolution

Allows building until licenser has a new release

* Import indra plugin classes instead of string applies

* remove space

Co-authored-by: broccolai <me@broccol.ai>

.github/workflows/gradle.yml

@@ -1,6 +1,3 @@
-# This workflow will build a Java project with Maven
-# For more information see: https://help.github.com/actions/language-and-framework-guides/building-and-testing-java-with-maven
-
 name: Java CI with Gradle
 
 on: [ push, pull_request ]
@@ -9,16 +6,14 @@ jobs:
   build:
     # Only run on PRs if the source branch is on someone else's repo
     if: ${{ github.event_name != 'pull_request' || github.repository != github.event.pull_request.head.repo.full_name }}
-    strategy:
-      matrix:
-        os: ["ubuntu-latest", "windows-latest"]
-    runs-on: "${{ matrix.os }}"
+    runs-on: "ubuntu-latest"
     steps:
       - uses: actions/checkout@v2
       - uses: gradle/wrapper-validation-action@v1
-      - name: Set up JDK 11
-        uses: actions/setup-java@v1
+      - name: Set up JDK 16
+        uses: actions/setup-java@v2
         with:
-          java-version: 11
+          distribution: 'adopt'
+          java-version: 16
       - name: Build with Gradle
         run: ./gradlew clean build