made dataBridgeSnapshot nullable

Author: Brandon Sneed

Segment/Classes/SEGMiddleware.h

@@ -76,6 +76,6 @@ NS_SWIFT_NAME(EdgeFunctionMiddleware)
 - (void)setEdgeFunctionData:(NSDictionary *_Nullable)data;
 - (void)addToDataBridge:(NSString * _Nonnull)key value:(id _Nonnull)value NS_SWIFT_NAME(addToDataBridge(key:value:));
 - (void)removeFromDataBridge:(NSString * _Nonnull)key NS_SWIFT_NAME(removeFromDataBridge(key:));
-- (NSDictionary<NSString *, id> * _Nonnull)dataBridgeSnapshot;
+- (NSDictionary<NSString *, id> * _Nullable)dataBridgeSnapshot;
 @end