Build(deps): Bump kotlin_version from 1.8.10 to 1.8.21

Bumps `kotlin_version` from 1.8.10 to 1.8.21.

Updates `org.jetbrains.kotlin:kotlin-gradle-plugin` from 1.8.10 to 1.8.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v1.8.10...v1.8.21)

Updates `org.jetbrains.kotlin:kotlin-stdlib` from 1.8.10 to 1.8.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](https://github.com/JetBrains/kotlin/compare/v1.8.10...v1.8.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -3,7 +3,7 @@ buildscript {
         androidPluginVersion = '7.4.2'
         appCompatVersion = '1.6.1'
         jacoco_version = '0.8.9'
-        kotlin_version = '1.8.10'
+        kotlin_version = '1.8.21'
         androidxTestVersion = "1.4.0"
         daggerVersion = "2.45"
         markwonVersion = "4.6.2"