(v3.6.x): Bump nl.jqno.equalsverifier:equalsverifier

Bumps [nl.jqno.equalsverifier:equalsverifier](https://github.com/jqno/equalsverifier) from 3.15.5 to 3.15.6.
- [Release notes](https://github.com/jqno/equalsverifier/releases)
- [Changelog](https://github.com/jqno/equalsverifier/blob/main/CHANGELOG.md)
- [Commits](jqno/equalsverifier@equalsverifier-3.15.5...equalsverifier-3.15.6)

---
updated-dependencies:
- dependency-name: nl.jqno.equalsverifier:equalsverifier
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -26,7 +26,7 @@ buildscript {
 		// Test Dependencies
 		springCloudContractVersion = "3.1.9"
 		javaHamcrestVersion = "2.0.0.0"
-		equalsVerifierVersion = "3.15.5"
+		equalsVerifierVersion = "3.15.6"
 		findbugsVersion = "3.0.1"
 
 		// Static Analysis