Added Gradle to Groovy project.

Groovy/build.gradle

@@ -0,0 +1,22 @@
+plugins {
+    id 'groovy'
+}
+
+repositories {
+    mavenCentral()
+}
+
+sourceCompatibility = '1.8'
+targetCompatibility = '1.8'
+group='com.gildedrose'
+
+dependencies {
+    implementation 'org.codehaus.groovy:groovy:3.0.12'
+
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.6.2'
+    testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.6.2'
+}
+
+test {
+    useJUnitPlatform()
+}