Use jdk 8 toolchain & add plugins to version catalog

Author: jpenilla

build.gradle.kts

@@ -1,7 +1,7 @@
 plugins {
     `kotlin-dsl`
     `maven-publish`
-    id("com.gradle.plugin-publish") version "1.2.1"
+    alias(libs.plugins.gradle.plugin.publish)
 }
 
 dependencies {
@@ -19,7 +19,7 @@ tasks.withType<JavaCompile>().configureEach {
 
 kotlin {
     jvmToolchain {
-        languageVersion = JavaLanguageVersion.of(17)
+        languageVersion = JavaLanguageVersion.of(8)
     }
     target {
         compilations.configureEach {

gradle/libs.versions.toml

@@ -1,3 +1,6 @@
+[plugins]
+gradle-plugin-publish = { id = "com.gradle.plugin-publish", version = "1.2.1" }
+
 [versions]
 indra = "3.1.3"
 gradleErrorprone = "3.1.0"