feat: add guild member banner field

[mifuyutsuki]

Pull Request Type

• Feature addition
• Bugfix
• Documentation update
• Code refactor
• Tests improvement
• CI/CD pipeline enhancement
• Other: [Replace with a description]

Description

Discord has added a banner field to the Guild Member object, making it fetchable. This pull request exposes and adds the field to the library Member object.

Changes

• Add attr guild_banner and property banner to Member
  • Behavior of banner is similar to display_avatar, defaulting to server banner before getting the global banner
  • Choice of name banner is for consistency with User
  • Edited user.pyi accordingly

Related Issues

#1674 (closed - predates API addition)

Test Scenarios

This creates a slash command /banner that fetches your banner (requires Nitro), if any.

from interactions import Client, slash_command, Embed

bot = Client()

@slash_command(name="banner", description="View your banner")
async def banner_cmd(ctx):
  e = Embed(f"Banner for {ctx.author.tag}")

  if ctx.author.banner:
    e.set_image(ctx.author.banner.url)
  else:
    e.description = "User has no banner."

  return await ctx.send(embed=e)

bot.start("token")

Python Compatibility

• I've ensured my code works on Python 3.10.x
• I've ensured my code works on Python 3.11.x

Checklist

• I've run the pre-commit code linter over all edited files
• I've tested my changes on supported Python versions
• I've added tests for my code, if applicable
• I've updated / added documentation, where applicable