Bump gradle from 4.2.2 to 7.0.2

Bumps gradle from 4.2.2 to 7.0.2.

---
updated-dependencies:
- dependency-name: com.android.tools.build:gradle
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

build.gradle

@@ -12,7 +12,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:4.2.2'
+        classpath 'com.android.tools.build:gradle:7.0.2'
         classpath 'com.google.gms:google-services:4.3.10'
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
         classpath 'org.sonarsource.scanner.gradle:sonarqube-gradle-plugin:3.3'