Add publishing to build.gradle.

Author: netomi

build.gradle

@@ -117,3 +117,21 @@ repositories {
     mavenCentral()
     jcenter()
 }
+
+publishing {
+    repositories {
+        maven {
+            name = "GitHubPackages"
+            url = uri("https://maven.pkg.github.com/netomi/sudoku-solver")
+            credentials {
+                username = project.findProperty("gpr.user") ?: System.getenv("USERNAME")
+                password = project.findProperty("gpr.key") ?: System.getenv("TOKEN")
+            }
+        }
+    }
+    publications {
+        gpr(MavenPublication) {
+            from(components.kotlin)
+        }
+    }
+}