Bump org.spongepowered:spongeapi from 8.1.0 to 12.0.0 in /Plan

Bumps [org.spongepowered:spongeapi](https://github.com/SpongePowered/SpongeAPI) from 8.1.0 to 12.0.0.
- [Release notes](https://github.com/SpongePowered/SpongeAPI/releases)
- [Commits](SpongePowered/SpongeAPI@v8.1.0...v12.0.0)

---
updated-dependencies:
- dependency-name: org.spongepowered:spongeapi
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Plan/build.gradle

@@ -76,7 +76,7 @@ subprojects {
         bukkitVersion = "1.13.2-R0.1-SNAPSHOT"
         spigotVersion = "1.13.2-R0.1-SNAPSHOT"
         paperVersion = "1.13.2-R0.1-SNAPSHOT"
-        spongeVersion = "8.1.0"
+        spongeVersion = "12.0.0"
         nukkitVersion = "1.0-SNAPSHOT"
         bungeeVersion = "1.16-R0.4"
         velocityVersion = "3.0.0-SNAPSHOT"