Updates httplib dependency to 0.15.3

[clanofartisans]

I affirm:

• I understand that if I do not agree to the following points by completing the checkboxes my PR will be ignored.
• I understand I should leave resolving conversations to the LandSandBoat team so that reviewers won't miss what was said.
• I have read and understood the Contributing Guide and the Code of Conduct.
• I have tested my code and the things my code has changed since the last commit in the PR and will test after any later commits.

What does this pull request do?

Updates the yhirose/cpp-httplib dependency to the most recent release.

Steps to test these changes

Enable the world HTTP server in network.lua, start the world server, hit the endpoints provided and make sure everything works as expected.

• /api
• /api/zones
• /api/zones/230
• /api/settings
• /api/bad_endpoint (should throw 404)

[zach2good]

I'm not against bumping deps versions, but was there a specific reason for this?

[clanofartisans]

I'm not against bumping deps versions, but was there a specific reason for this?

Honestly, we just had something downstream using a different version and I wanted to clean that up. Updating both Horizon and LSB seemed the most expedient way to get everything lined up. I completely understand if that's not a good enough reason to update LSB and won't be surprised if you just close this :)