fix: use media.discordapp.net for gif stickers

[shiftinv]

Summary

https://github.com/discord/discord-api-docs/commit/0a7d731bad7d49c2e49b0687d2a9ec633efeabc9

Checklist

• [x] If code changes were made, then they have been tested
  • [ ] I have updated the documentation to reflect the changes
  • [x] I have formatted the code properly by running pdm lint
  • [x] I have type-checked the code by running pdm pyright
• [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, ...)