fix: further address audit log issues

[NeloBlivion]

Summary

Any fixes to audit logs should require heavy scrutiny, please test thoroughly before approving.

Makes further adjustments to audit log logic:

• after reverses the sort to oldest first IF AND ONLY IF before is not passed. In this instance, it should redefine after as the last item instead of the first. Discord's language on this in their docs is easy to misunderstand.
• Adjusted http request to accept 0 as a valid snowflake (as officially recommended)
• Reverted _get_retrieve changes as the new method was not reliable, resulting in extra requests.

While i have tested this PR, it still needs further testing for guilds with extensive audit logs and thus higher limits above 100.

Information

• [x] This PR fixes an issue.
• [ ] This PR adds something new (e.g. new method or parameters).
• [ ] This PR is a breaking change (e.g. methods or parameters removed/renamed).
• [ ] This PR is not a code change (e.g. documentation, README, typehinting, examples, ...).

Checklist

• [x] I have searched the open pull requests for duplicates.
• [x] If code changes were made then they have been tested.
  • [ ] I have updated the documentation to reflect the changes.
• [ ] If type: ignore comments were used, a comment is also left explaining why.
• [x] I have updated the changelog to include these changes.

[Dorukyum]

Tested on the Pycord server.

[NeloBlivion]

The logic was further adjusted:

• if the user only specifies before, then we update self.before on every iteration with last item
• if the user only specifies after, we update self.after on every iteration with last item
• if the user specifies both or neither, follow the first point.

This change has no practical difference compared to the initial commit, but it's easier to wrap your head around.

[Dorukyum]

Tested on the Pycord server again:

• only before: newest first
• only after: oldest first
• both: newest first
• neither: newest first