fix: Tag fetching

[Alystrasz]

META PR, NO MOD VERIFICATION NEEDED

While checking tags, if current tag isn't found in first page, script will now browse all API pages until either tag is found or there are no more pages.

I also added a few tests to ensure correct method behaviour. Moved to #34

Closes #17.

[GeckoEidechse]

I'm maybe gonna split this PR up a bit before merging ^^

Also, I think for unit testing there's some frameworks like pytest that make it a bit nicer so that we don't have to pass a CLI arg to run unittest. Then we can also combine it with our current CI to always run meta tests for verification scripts ^^

[Alystrasz]

Then we can also combine it with our current CI to always run meta tests for verification scripts

I feel like this is overkill tbh, the idea was to ensure new function behaves properly during development.

[GeckoEidechse]

I'm gonna remove the testing into separate PR and then merge this one ^^

[GeckoEidechse]

Aight, I think I have massacred this PR enough now xD

Anyway, code works and as far as I can tell the logic is correct ^^

The unit testing code for this will be added in a separate PR.

[GeckoEidechse]

Also I'll change the .format() parts to f-strings as well in a separate PR ^^