Bump org.gretty:gretty from 4.1.5 to 4.1.6

Bumps [org.gretty:gretty](https://github.com/gretty-gradle-plugin/gretty) from 4.1.5 to 4.1.6.
- [Release notes](https://github.com/gretty-gradle-plugin/gretty/releases)
- [Changelog](https://github.com/gretty-gradle-plugin/gretty/blob/master/changes.md)
- [Commits](https://github.com/gretty-gradle-plugin/gretty/compare/v4.1.5...v4.1.6)

---
updated-dependencies:
- dependency-name: org.gretty:gretty
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

buildSrc/build.gradle

@@ -83,7 +83,7 @@ dependencies {
 
     implementation 'io.github.gradle-nexus:publish-plugin:1.1.0'
     implementation 'io.projectreactor:reactor-core:3.4.41'
-    implementation ('org.gretty:gretty:4.1.5') {
+    implementation ('org.gretty:gretty:4.1.6') {
         exclude group: 'org.springframework.boot', module: 'spring-boot-loader-tools'
     }
     implementation 'com.apollographql.apollo:apollo-runtime:2.4.6'