Update build.gradle

Author: passplease

build.gradle

@@ -207,8 +207,7 @@ tasks.withType(JavaCompile).configureEach {
 import com.bmuschko.gradle.docker.tasks.image.DockerBuildImage
 import com.bmuschko.gradle.docker.tasks.image.DockerPushImage
 
-def imageName = "ghcr.io/${System.getenv("PROJECT_NAME")}:${mod_version}"
-imageName.replaceAll('-','_')
+def imageName = "ghcr.io/${System.getenv("PROJECT_NAME")}:${mod_version}".toLowerCase()
 
 tasks.register('buildDockerImage', DockerBuildImage) {
     inputDir = project.projectDir