Bump com.approvaltests:approvaltests from 24.15.0 to 24.21.0 (#268)

Bumps [com.approvaltests:approvaltests](https://github.com/approvals/ApprovalTests.Java) from 24.15.0 to 24.21.0.
- [Release notes](https://github.com/approvals/ApprovalTests.Java/releases)
- [Commits](approvals/ApprovalTests.Java@24.15.0...24.21.0)

---
updated-dependencies:
- dependency-name: com.approvaltests:approvaltests
  dependency-version: 24.21.0
  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>

Author: dependabot[bot]

build.gradle

@@ -21,7 +21,7 @@ dependencies {
     testImplementation platform("org.junit:junit-bom:5.11.4")
     testImplementation "org.junit.jupiter:junit-jupiter"
     testImplementation "org.assertj:assertj-core:3.27.0"
-    testImplementation "com.approvaltests:approvaltests:24.15.0"
+    testImplementation "com.approvaltests:approvaltests:24.21.0"
 }
 
 shadowJar {