Bump gradle from 7.0.3 to 7.0.4 (#366)

Bumps gradle from 7.0.3 to 7.0.4.

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

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build.gradle

@@ -5,7 +5,7 @@ buildscript {
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:7.0.3'
+        classpath 'com.android.tools.build:gradle:7.0.4'
         classpath 'com.google.gms:google-services:4.3.10'
     }
 }