Bump third_party/imgui/repo from 2860d7b to 4819eae

Bumps [third_party/imgui/repo](https://github.com/ocornut/imgui) from `2860d7b` to `4819eae`.
- [Release notes](https://github.com/ocornut/imgui/releases)
- [Commits](ocornut/imgui@2860d7b...4819eae)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

third_party/imgui/repo

@@ -0,0 +1 @@
+4819eae8674209f7ddf70cd9a8b2e10528405fff