Update credentials handling in Gradle and Jenkinsfile for improved security

settings.gradle.kts

@@ -16,7 +16,10 @@ dependencyResolutionManagement {
         maven { // mypet
             name = "GitHubPackages"
             url = uri("https://maven.pkg.github.com/MyPetORG/MyPet")
-            credentials(PasswordCredentials::class)
+            credentials {
+                username = providers.gradleProperty("GitHubPackagesUsername").orNull
+                password = providers.gradleProperty("GitHubPackagesPassword").orNull
+            }
         }
 
     }