chore: Add Gradle plugin maven publish for versioning and publishing to GitHub package registry

build.gradle

@@ -3,10 +3,11 @@ import java.text.SimpleDateFormat
 plugins {
     id 'java'
     id 'idea'
+
+    id 'maven-publish'
 }
 
 group 'de.griefed'
-version '1.0-SNAPSHOT'
 
 //noinspection GroovyUnusedAssignment
 sourceCompatibility = targetCompatibility = '1.8'
@@ -95,4 +96,27 @@ jar {
             'META-INF/README.md',
             'Log4j-**'
     )
+}
+
+// Publish the package with passed version to GHPR. Use ./gradlew -Pversion=${NEW_VERSION} publish, for example.
+publishing {
+    repositories {
+        maven {
+            name = "GitHubPackages"
+            url = uri("https://maven.pkg.github.com/Griefed/serverpackcreatorexampleaddon")
+            credentials {
+                username = System.getenv("GITHUB_ACTOR")
+                password = System.getenv("GITHUB_TOKEN")
+            }
+        }
+    }
+    publications {
+        //noinspection GroovyAssignabilityCheck
+        gpr(MavenPublication) {
+            //noinspection GroovyAssignabilityCheck
+            artifactId='serverpackcreatorexampleaddon'
+            //noinspection GroovyAssignabilityCheck
+            from (components.java)
+        }
+    }
 }
\ No newline at end of file

settings.gradle

-rootProject.name = 'ServerPackCreatorExampleAddon'
+rootProject.name = 'serverpackcreatorexampleaddon'