fix: call the gradle wrapper correctly on windows (#175)

Author: Chad Morrow

packages/react-native-builder-bob/src/utils/androidAssemble.ts

@@ -24,8 +24,7 @@ export default async function androidAssemble({
     )}`
   );
 
-  const gradleWrapper =
-    './gradlew' + (platform() === 'win32' ? './gradlew.bat' : '');
+  const gradleWrapper = platform() === 'win32' ? 'gradlew.bat' : './gradlew';
   if (await fs.pathExists(path.join(androidPath, gradleWrapper))) {
     execFileSync(gradleWrapper, ['assemble'], { cwd: androidPath });
   } else {