chore(deps): bump kotlin_version from 1.4.20 to 1.4.21-2 in /snippets (#411)

Bumps `kotlin_version` from 1.4.20 to 1.4.21-2.

Updates `kotlin-gradle-plugin` from 1.4.20 to 1.4.21-2
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.4.21-2)

Updates `kotlin-stdlib` from 1.4.20 to 1.4.21-2
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.4.20...v1.4.21-2)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

snippets/build.gradle

@@ -1,6 +1,6 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 buildscript {
-    ext.kotlin_version = "1.4.20"
+    ext.kotlin_version = "1.4.21-2"
     repositories {
         google()
         jcenter()