build(deps): update gevent requirement from <27,>=26.7.0 to >=26.8.0,<27

Updates the requirements on [gevent](https://github.com/gevent/gevent) to permit the latest version.
- [Release notes](https://github.com/gevent/gevent/releases)
- [Changelog](https://github.com/gevent/gevent/blob/master/docs/changelog_pre.rst)
- [Commits](gevent/gevent@26.7.0...26.8.0)

---
updated-dependencies:
- dependency-name: gevent
  dependency-version: 26.8.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements/testing.txt

@@ -3,5 +3,5 @@ pytest>=8,<9; python_version == "3.9"
 pytest>=9.1.1,<10; python_version >= "3.10"
 pytest-cov>=7.1.0,<8
 Flask>=3.1.3,<4 
-gevent>=26.7.0,<27
+gevent>=26.8.0,<27
 gevent-websocket>=0.10.1,<1