Bump org.spongepowered.gradle.plugin from 2.1.1 to 2.2.0 (#494)

Bumps [org.spongepowered.gradle.plugin](https://github.com/SpongePowered/SpongeGradle) from 2.1.1 to 2.2.0.
- [Release notes](https://github.com/SpongePowered/SpongeGradle/releases)
- [Commits](SpongePowered/SpongeGradle@v2.1.1...v2.2.0)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

sponge/build.gradle

@@ -2,7 +2,7 @@ import org.spongepowered.gradle.plugin.config.PluginLoaders
 import org.spongepowered.plugin.metadata.model.PluginDependency
 
 plugins {
-    id 'org.spongepowered.gradle.plugin' version '2.1.1'
+    id 'org.spongepowered.gradle.plugin' version '2.2.0'
 }
 
 dependencies {