Project property value can only be strings.

Fix
> Failed to notify project evaluation listener.
   > Could not create task ':element-android:matrix-sdk-android:compileDebugAndroidTestKotlin'.
      > Could not create task of type 'KotlinCompile'.
         > class java.util.LinkedHashMap cannot be cast to class java.lang.String (java.util.LinkedHashMap and java.lang.String are in module java.base of loader 'bootstrap')

vector-app/build.gradle

@@ -232,7 +232,7 @@ android {
             resValue "color", "launcher_background", "#0DBD8B"
 
             if (project.hasProperty("coverage")) {
-                testCoverageEnabled = coverage.enableTestCoverage
+                testCoverageEnabled = coverage == "true"
             }
         }