fix(plugin-development): Add GradleUp shadow alias

Fixes #87

Author: zml2008

plugin-development/src/main/java/org/spongepowered/gradle/common/Constants.java

@@ -53,6 +53,7 @@ private Dependencies() {
 
     public static final class Plugins {
         public static final List<String> SHADOW_PLUGIN_IDS = Collections.unmodifiableList(Arrays.asList(
+                "com.gradleup.shadow",
                 "com.github.johnrengelman.shadow",
                 "io.github.goooler.shadow"
         ));