fix: broken gradle CI

.github/workflows/gradle.yml

@@ -2,24 +2,26 @@ name: Lint & Test with Gradle
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
 
 jobs:
   gradle:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java-version: ['11', '17']
+        java-version:
+          - 17
+          - 21
 
     steps:
       - uses: actions/checkout@v4
       - name: Install JDK
         uses: actions/setup-java@v4
         with:
           java-version: ${{ matrix.java-version }}
-          distribution: 'adopt'
+          distribution: "adopt"
       - name: Lint
         run: gradle spotlessCheck
       - name: Build & Test
-        run: gradle test -x spotlessApply
+        run: gradle test -x spotlessApply --info

.github/workflows/mvn.yml

@@ -2,23 +2,26 @@ name: Lint & Test with Maven
 
 on:
   push:
-    branches: [ main ]
+    branches: [main]
   pull_request:
 
 jobs:
   mvn:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        java-version: ['11', '17']
+        java-version:
+          - 11
+          - 17
+          - 21
 
     steps:
       - uses: actions/checkout@v4
       - name: Install JDK
         uses: actions/setup-java@v4
         with:
           java-version: ${{ matrix.java-version }}
-          distribution: 'adopt'
+          distribution: "adopt"
       - name: Lint
         run: mvn --batch-mode spotless:check
       - name: Build & Test

build.gradle

@@ -22,16 +22,21 @@ dependencies {
 	// ***** OAUTH DEPENDENCIES *****
 	implementation("com.slack.api:bolt-jetty:1.45.3")
 	// ***** TEST DEPENDENCIES *****
-	testImplementation('org.junit.jupiter:junit-jupiter-engine:5.13.4')
+	testImplementation('org.junit.jupiter:junit-jupiter-api:5.13.4')
+	testRuntimeOnly('org.junit.jupiter:junit-jupiter-engine:5.13.4')
 	testImplementation('org.mockito:mockito-core:5.18.0')
 }
 
 application {
 	mainClass = 'Main'
 }
 
-tasks.named('test') {
-	useJUnit()
+testing {
+	suites {
+		test {
+			useJUnitJupiter()
+		}
+	}
 }
 
 spotless {