chore: Set up the Maven Publish plugin

The last version we used to publish was 0.2.3, so I bumped the version
to 0.3.0 due to all the breaking changes that were made when porting
everything from Scala to Kotlin.

Author: robinlinden

lib/build.gradle.kts

@@ -4,8 +4,14 @@ plugins {
 
     // Apply the java-library plugin for API and implementation separation.
     `java-library`
+
+    // https://docs.gradle.org/current/userguide/publishing_maven.html
+    `maven-publish`
 }
 
+group = "org.toktok"
+version = "0.3.0"
+
 repositories {
     // Use Maven Central for resolving dependencies.
     mavenCentral()
@@ -33,3 +39,12 @@ testing {
         }
     }
 }
+
+publishing {
+    publications {
+        create<MavenPublication>("maven") {
+            artifactId = "tox4j-c"
+            from(components["java"])
+        }
+    }
+}