Remove urllib3 info from useragent string

[jhamon]

Problem

• Currently we send urllib3 version in the user agent string
• Testing with importtime shows importing urllib3 just to get the version extends the initial load time of the pinecone package by about 35 milliseconds.

Solution

I confirmed we're not using this information in the header, so we should remove it to improve initialization performance.

Test Plan

• Analysis with showed Loading this urllib3 to get the version was adding 35 milliseconds to the time needed to "from pinecone import Pinecone"
• Updated unit tests

[jhamon]

I'm merging this with failures; failing tests are unrelated and I've filed a bug with the backend team.