Fix spotbugs warning about \n vs %n.

Author: nedtwigg

plugin-gradle/src/main/java/com/diffplug/gradle/spotless/GradleProvisioner.java

@@ -128,7 +128,7 @@ private static Provisioner forConfigurationContainer(Project project, Configurat
 					projName = projName + "/";
 				}
 				throw new GradleException(String.format(
-						"You need to add a repository containing the '%s' artifact in '%sbuild.gradle'.\n" +
+						"You need to add a repository containing the '%s' artifact in '%sbuild.gradle'.%n" +
 								"E.g.: 'repositories { mavenCentral() }'",
 						mavenCoords, projName), e);
 			}