build(deps): Bump external/imgui from 368123a to 8082a84

Bumps [external/imgui](https://github.com/ocornut/imgui) from `368123a` to `8082a84`.
- [Release notes](https://github.com/ocornut/imgui/releases)
- [Commits](ocornut/imgui@368123a...8082a84)

---
updated-dependencies:
- dependency-name: external/imgui
  dependency-type: direct:production
...

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