Bump org.spongepowered.gradle.plugin from 2.2.0 to 2.3.0 in /Plan

Bumps [org.spongepowered.gradle.plugin](https://github.com/SpongePowered/SpongeGradle) from 2.2.0 to 2.3.0.
- [Release notes](https://github.com/SpongePowered/SpongeGradle/releases)
- [Commits](SpongePowered/SpongeGradle@v2.2.0...v2.3.0)

---
updated-dependencies:
- dependency-name: org.spongepowered.gradle.plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Plan/sponge/build.gradle

@@ -2,7 +2,7 @@ import org.spongepowered.gradle.plugin.config.PluginLoaders
 import org.spongepowered.gradle.vanilla.repository.MinecraftPlatform
 
 plugins {
-    id "org.spongepowered.gradle.plugin" version "2.2.0"
+    id "org.spongepowered.gradle.plugin" version "2.3.0"
     id "org.spongepowered.gradle.vanilla" version "0.2.1-SNAPSHOT"
 }