Feat/replace requests with urllib3

[vinitkumar]

• Remove requests as a dependency and use urllib3, since it much better development and funded as well.

[codecov[bot]]

Codecov Report

Base: 94.02% // Head: 94.04% // Increases project coverage by +0.01% :tada:

Coverage data is based on head (309795c) compared to base (18a5c19). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #167 +/- ## ========================================== + Coverage 94.02% 94.04% +0.01% ========================================== Files 6 6 Lines 536 537 +1 ========================================== + Hits 504 505 +1 Misses 32 32 ``` | [Impacted Files](https://codecov.io/gh/vinitkumar/json2xml/pull/167?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Vinit+Kumar) | Coverage Δ | | |---|---|---| | [json2xml/utils.py](https://codecov.io/gh/vinitkumar/json2xml/pull/167?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Vinit+Kumar#diff-anNvbjJ4bWwvdXRpbHMucHk=) | `86.04% <100.00%> (+0.33%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Vinit+Kumar). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Vinit+Kumar)

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