TurboModules: use weakSelf for block sent to main thread

Summary:
TurboModules: use weakSelf for block sent to main thread.

Changelog:
[iOS][Fixed] - Use weakSelf in objc block instead of self.

Reviewed By: RSNara

Differential Revision: D33488938

fbshipit-source-id: d03c98fb59fbd1fc4b67686251ebec541e5d3e6c

Author: Moses DeJong

ReactCommon/react/nativemodule/core/platform/ios/RCTTurboModuleManager.mm

@@ -437,10 +437,15 @@ - (TurboModuleHolder *)_getOrCreateTurboModuleHolder:(const char *)moduleName
     __block id<RCTTurboModule> module = nil;
 
     if ([moduleClass conformsToProtocol:@protocol(RCTTurboModule)]) {
+      __weak __typeof(self) weakSelf = self;
       dispatch_block_t work = ^{
-        module = [self _createAndSetUpRCTTurboModule:moduleClass
-                                          moduleName:moduleName
-                                            moduleId:moduleHolder->getModuleId()];
+        auto strongSelf = weakSelf;
+        if (!strongSelf) {
+          return;
+        }
+        module = [strongSelf _createAndSetUpRCTTurboModule:moduleClass
+                                                moduleName:moduleName
+                                                  moduleId:moduleHolder->getModuleId()];
       };
 
       if ([self _requiresMainQueueSetup:moduleClass]) {