chore(deps-dev): update starlette requirement

Updates the requirements on [starlette](https://github.com/Kludex/starlette) to permit the latest version.
- [Release notes](https://github.com/Kludex/starlette/releases)
- [Changelog](https://github.com/Kludex/starlette/blob/main/docs/release-notes.md)
- [Commits](Kludex/starlette@0.49.3...1.6.0)

---
updated-dependencies:
- dependency-name: starlette
  dependency-version: 1.6.0
  dependency-type: direct:development
...

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

Author: dependabot[bot]

requirements/adapter_dev.txt

@@ -66,7 +66,7 @@ sanic>=25.12.1,<26; python_version >= "3.10"
 # starlette
 # Note: starlette 0.49.3 requires Python >=3.9; 3.7/3.8 stay on the older pinned release.
 starlette>=0.19.1,<0.45; python_version < "3.9"
-starlette>=0.49.3,<1; python_version >= "3.9"
+starlette>=1.6.0,<2; python_version >= "3.9"
 
 # tornado
 # Note: tornado 6.5.6 requires Python >=3.9; 3.7/3.8 stay on the older pinned release.