Bump com.puppycrawl.tools:checkstyle from 10.20.2 to 10.21.1 (#131)

Bumps [com.puppycrawl.tools:checkstyle](https://github.com/checkstyle/checkstyle) from 10.20.2 to 10.21.1.
- [Release notes](https://github.com/checkstyle/checkstyle/releases)
- [Commits](checkstyle/checkstyle@checkstyle-10.20.2...checkstyle-10.21.1)

---
updated-dependencies:
- dependency-name: com.puppycrawl.tools:checkstyle
  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>

app/build.gradle

@@ -2,7 +2,7 @@ buildscript {
     dependencies {
         classpath 'com.android.tools.build:gradle:8.7.3'
         classpath 'com.github.spotbugs.snom:spotbugs-gradle-plugin:6.0.27'
-        classpath 'com.puppycrawl.tools:checkstyle:10.20.2'
+        classpath 'com.puppycrawl.tools:checkstyle:10.21.1'
     }
 }