Added Marathi language code

Author: rizafran

FirebaseRemoteConfig/Sources/RCNDevice.m

@@ -104,6 +104,8 @@ RCNDeviceModel FIRRemoteConfigDeviceSubtype(void) {
     @"ms" : @[ @"ms_MY" ],
     // Maltese
     @"mt" : @[ @"mt_MT" ],
+    // Marathi
+       @"mr" : @[ @"mr_IN" ],
     // Polish
     @"pl" : @[ @"pl", @"pl_PL", @"pl-PL" ],
     // Romanian