Add version tracking and user agent to requests session

[zurawiki]

TL;DR

Added User-Agent headers to API requests with version and git SHA information (to make traffic identification easier)

What changed?

• Added __version__ variable to track the package version
• Implemented helper functions to get the git SHA of the current commit
• Created a function to build a User-Agent string that includes version and git SHA
• Replaced individual requests calls with a shared session that includes the User-Agent header
• Moved the requests import to the top-level module

How to test?

TODO

[zurawiki]

• Add version tracking and user agent to requests session #150 👈 (View in Graphite)
• main

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