fix invoke issue.

ios/Classes/FlutterQrPlugin.m

@@ -1,5 +1,11 @@
 #import "FlutterQrPlugin.h"
-#import "qr_code_scanner/qr_code_scanner-Swift.h"
+
+#if __has_include(<qr_code_scanner/qr_code_scanner-Swift.h>)
+#import <qr_code_scanner/qr_code_scanner-Swift.h>
+#else
+#import "qr_code_scanner-Swift.h"
+#endif
+
 @implementation FlutterQrPlugin
 + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
     [SwiftFlutterQrPlugin registerWithRegistrar:registrar];