fix: getUserAgent regex

Brief Summary of Changes

Improved the regexp that tests the user agent header added to the requests. It should match all versions that are correct in term of semantic versioning, including prerelease modifiers and their versions.

What Does This PR Address?

[ ] GitHub issue (Add reference - #XX)
[ ] Refactoring
[ ] New feature
[X] Bug fix
[ ] Adds more tests

Are Tests Included?

[X] Yes
[ ] No

cloudinary / cloudinary_npm

fix: getUserAgent regex #647

Brief Summary of Changes

What Does This PR Address?

Are Tests Included?

Reviewer, Please Note: