Fix typo in README.md

[baseplate-admin]

Hi there,

In your README.md you are using :: ( double colons ), where it should be : ( one colon ) after https to get proper redirects.

https:://github.com/go-python/gopy ⚔️  # Wrong
https://github.com/go-python/gopy 👌   # Correct

This pull request essentially fixes that.