Bump embedded_kotlin_version from 1.6.20 to 1.6.21

Bumps `embedded_kotlin_version` from 1.6.20 to 1.6.21.

Updates `kotlin-scripting-compiler` from 1.6.20 to 1.6.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.6.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.6.20...v1.6.21)

Updates `kotlin-compiler-embeddable` from 1.6.20 to 1.6.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.6.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.6.20...v1.6.21)

Updates `kotlin-annotation-processing-embeddable` from 1.6.20 to 1.6.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v1.6.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.6.20...v1.6.21)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-scripting-compiler
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-compiler-embeddable
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-annotation-processing-embeddable
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

build.gradle

@@ -1,6 +1,6 @@
 buildscript {
     ext.kotlin_version = '1.6.20'
-    ext.embedded_kotlin_version =  '1.6.20'
+    ext.embedded_kotlin_version =  '1.6.21'
 
     repositories {
         mavenCentral()