perf: if image has been uploaded, return image url insead of error

[tisfeng]

Summary of this pull request

If the uploaded image name is duplicated, an error message will prompt that "sha wasn't supplied". The recent update made the following optimizations:

1. If the uploaded image name already exists and has the same sha value, it will directly return the URL of that image.
2. If the uploaded image name already exists but has a different sha value (indicating a different image with the same name), it will upload again with a randomly generated image name.

I tested it and it runs well, so I released an updated version 1.4.3 , just in case any other users might need it.

Does this solve an existing issue? If so, add a link to it

Refer to #238

Steps to test this feature

Screenshots

Additional info