ci: use a repository cache (Resolves #319)

Author: Steve Ramage

ci/release.Jenkinsfile

@@ -345,7 +345,7 @@ pipeline {
             sh("""
               mkdir -p ./build
               ./generate-changelog  > build/CHANGELOG
-              ./gradlew --no-daemon -I ./build-cache-init.gradle.kts --build-cache build buildPlugin --scan
+              ./gradlew --no-daemon -I ./build-cache-init.gradle.kts -I ./repo-cache-init.gradle.kts --build-cache build buildPlugin --scan
               """)
             script {
               if (env.BRANCH_NAME ==~ /^([0-9][0-9][0-9]\.x)$/) {

repo-cache-init.gradle.kts

@@ -0,0 +1,17 @@
+val nexusRepo = System.getenv("NEXUS_REPO")
+
+if (nexusRepo != null) {
+  println("🔗 Using Nexus repo at: $nexusRepo")
+  allprojects {
+    buildscript {
+      repositories {
+        maven { url = uri("$nexusRepo/repository/gradle-plugin/") }
+      }
+    }
+    repositories {
+      maven { url = uri("$nexusRepo/repository/maven-central/") }
+    }
+  }
+} else {
+  println("⚠️ NEXUS_REPO is not set. Using default repositories.")
+}