Use LeakCanary in debug mode

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

build.gradle

@@ -338,6 +338,8 @@ dependencies {
         }
     }
 
+    debugImplementation 'com.squareup.leakcanary:leakcanary-android:2.7'
+
     // dependencies for local unit tests
     testImplementation 'junit:junit:4.13.2'
     testImplementation "org.mockito:mockito-core:$mockitoVersion"