Remove `urllib3` dependency for `requests` functionality about prometheus-eaton-ups-exporter

[TobiasKadelka]

I think the comment above is partly wrong.

The eaton ups exporter already uses requests to disable the SSL verification with:
self.session.verify = not insecure # ignore self signed certificate, but this is not what it uses urllib3 for.

When using requests session.verify = False this means SSL verification is ignored, which the people of requests discussed, and they decided that that makes a warning about this behavior necessary.

It is possible to use urllib3.disable_warnings() to disable these warnings -> and this is what is what the eaton ups exporter is doing and what urllib3 is used for.

[TobiasKadelka]

Discussion about this in requests: psf/requests#2214

To remove the dependency we could just allow the warning to happen.

[aqw]

Ahh, thanks for sharing that. Indeed that's different than I thought.

I would prefer a solution more in the line of one of these two:

• https://stackoverflow.com/a/43269398
• psf/requests#2214 (comment)

They both solve this problem different ways, but in common, they import from the requests namespace, which makes the intent and relation more obvious.

[nhjjr]

urllib3 is a dependency for requests, so it's going to be part of the package environment anyway, but I vastly prefer the solution @aqw suggested. Note that this is a remnant directly copied from the Raritan PDU Exporter back when it used requests and multi-threading instead of aiohttp and asynchronous operations.

Perhaps it is worth considering doing the same for this exporter, if the time investment is deemed worthwhile.