fix: bump kotlin_version from 1.7.20 to 1.7.21

Bumps `kotlin_version` from 1.7.20 to 1.7.21.

Updates `kotlin-gradle-plugin` from 1.7.20 to 1.7.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.7.20...v1.7.21)

Updates `kotlin-stdlib-jdk8` from 1.7.20 to 1.7.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.7.20...v1.7.21)

Updates `kotlin-reflect` from 1.7.20 to 1.7.21
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/master/ChangeLog.md)
- [Commits](JetBrains/kotlin@v1.7.20...v1.7.21)

---
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-jdk8
  dependency-type: direct:production
  update-type: version-update:semver-patch
- dependency-name: org.jetbrains.kotlin:kotlin-reflect
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

build.gradle

@@ -4,7 +4,7 @@
  */
 
 buildscript {
-    ext.kotlin_version = '1.7.20'
+    ext.kotlin_version = '1.7.21'
     ext.sqldelight_version = '1.5.4'
 
     repositories {