Bump third_party/imgui/repo from `277ae93` to `fbf45ad` (#32402)

Bumps [third_party/imgui/repo](https://github.com/ocornut/imgui) from `277ae93` to `fbf45ad`.
- [Release notes](https://github.com/ocornut/imgui/releases)
- [Commits](https://github.com/ocornut/imgui/compare/277ae93c41314ba5f4c7444f37c4319cdf07e8cf...fbf45ad149b10ff8d9cb97aefe0dc5a9562fd66e)

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

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
diff --git a/third_party/imgui/repo b/third_party/imgui/repo
index 277ae93..fbf45ad 160000
--- a/third_party/imgui/repo
+++ b/third_party/imgui/repo
@@ -1 +1 @@
-Subproject commit 277ae93c41314ba5f4c7444f37c4319cdf07e8cf
+Subproject commit fbf45ad149b10ff8d9cb97aefe0dc5a9562fd66e