build: added ghp publication

Author: arimer

build.gradle

@@ -255,6 +255,20 @@ publishing {
             }
         }
     }
+    repositories {
+        if(currentBranch == "master" || currentBranch.startsWith("maintenance") || currentBranch.startsWith("mps")) {
+                maven {
+                    name = "GitHubPackages"
+                    url = uri("https://maven.pkg.github.com/IETS3/iets3.opensource")
+                    if(project.hasProperty("gpr.token")) {
+                        credentials {
+                            username = project.findProperty("gpr.user")
+                            password = project.findProperty("gpr.token")
+                        }
+                    }
+                }
+            }
+        }
 
     publications {
         openSource(MavenPublication) {