Bump io.objectbox:objectbox-gradle-plugin from 3.8.0 to 4.0.2

Bumps [io.objectbox:objectbox-gradle-plugin](https://github.com/objectbox/objectbox-java-generator) from 3.8.0 to 4.0.2.
- [Commits](objectbox/objectbox-java-generator@V3.8.0...V4.0.2)

---
updated-dependencies:
- dependency-name: io.objectbox:objectbox-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

app/build.gradle

@@ -1,6 +1,6 @@
 buildscript {
     dependencies {
-        classpath "io.objectbox:objectbox-gradle-plugin:3.8.0"
+        classpath "io.objectbox:objectbox-gradle-plugin:4.0.2"
     }
 }