Bump org.jetbrains.kotlin:kotlin-stdlib in /android (#256)

Bumps [org.jetbrains.kotlin:kotlin-stdlib](https://github.com/JetBrains/kotlin) from 2.0.20 to 2.0.21.
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Changelog](https://github.com/JetBrains/kotlin/blob/v2.0.21/ChangeLog.md)
- [Commits](JetBrains/kotlin@v2.0.20...v2.0.21)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

android/app/build.gradle

@@ -107,7 +107,7 @@ flutter {
 }
 
 dependencies {
-    implementation "org.jetbrains.kotlin:kotlin-stdlib:2.0.20"
+    implementation "org.jetbrains.kotlin:kotlin-stdlib:2.0.21"
     testImplementation 'junit:junit:4.13.2'
     // https://developer.android.com/jetpack/androidx/releases/test/#1.2.0