chore: add User-Agent header to all connect requests

[kwsantiago]

Fixes #1897

[pythcoiner]

Hi, thanks for the PR, I think you should use VERSION.to_string() so it's compatible w/ #1694

[kwsantiago]

Thank you for pointing that out @pythcoiner , I pushed up to reflect. fdd6a81

[pythcoiner]

tACK fdd6a81 on those requests:

• get_key_by_token()
• refresh_token()
• redeem_key()
• sign_in_otp()
• verify_otp()

[edouardparis]

Thank you @kwsantiago !