Bump kotlin_version from 1.5.31 to 1.6.10 in /android

Bumps `kotlin_version` from 1.5.31 to 1.6.10.

Updates `kotlin-gradle-plugin` from 1.5.31 to 1.6.10
- [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/v1.5.31...v1.6.10)

Updates `kotlin-stdlib-jdk7` from 1.5.31 to 1.6.10
- [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/v1.5.31...v1.6.10)

---
updated-dependencies:
- dependency-name: org.jetbrains.kotlin:kotlin-gradle-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: org.jetbrains.kotlin:kotlin-stdlib-jdk7
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

android/build.gradle

@@ -2,7 +2,7 @@ group 'net.touchcapture.qr.flutterqr'
 version '1.0-SNAPSHOT'
 
 buildscript {
-    ext.kotlin_version = '1.5.31'
+    ext.kotlin_version = '1.6.10'
     repositories {
         google()
         mavenCentral()