Bump kotlin_version from 1.3.72 to 1.4.0

Bumps `kotlin_version` from 1.3.72 to 1.4.0.

Updates `kotlin-gradle-plugin` from 1.3.72 to 1.4.0

Updates `kotlin-stdlib-jdk7` from 1.3.72 to 1.4.0
- [Release notes](https://github.com/JetBrains/kotlin/releases)
- [Commits](https://github.com/JetBrains/kotlin/commits)

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

build.gradle

@@ -8,7 +8,7 @@ import com.github.spotbugs.snom.SpotBugsTask
 // its root folder, another one for the app module in subfolder of root.
 
 buildscript {
-    ext.kotlin_version = '1.3.72'
+    ext.kotlin_version = '1.4.0'
     repositories {
         google()
         jcenter()