pip dev(deps-dev): bump pyright from 1.1.389 to 1.1.391 in /eng

Bumps [pyright](https://github.com/RobertCraigie/pyright-python) from 1.1.389 to 1.1.391.
- [Release notes](https://github.com/RobertCraigie/pyright-python/releases)
- [Commits](RobertCraigie/pyright-python@v1.1.389...v1.1.391)

---
updated-dependencies:
- dependency-name: pyright
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

packages/typespec-python/dev_requirements.txt

@@ -1,5 +1,5 @@
 # shall keep aligned with dev_requirements.txt of @typspec/http-client-python
-pyright==1.1.389
+pyright==1.1.391
 pylint==3.2.7
 tox==4.23.2
 mypy==1.13.0