[BUG] Can successfully import an existing workflow

[xingchun-chen]

*For better global communication, please give priority to using English description, thx! *

Describe the bug
Successfully import an existing workflow, importing an existing workflow should not succeed

To Reproduce

1. Enter the workflow definition page of project management, import an existing workflow, and import it successfully, as shown below:
   

Expected behavior
Cannot import an existing workflow

Which version of Easy Scheduler:
-[dev分支]

[davidzollo]

good job!

[fancyChuan]

I want to fix this bug by renaming the workflow to another name, like: xxx-copy

[chongchongzi]

I've fixed it. I'll submit it it later.