Bump imageio from 2.31.5 to 2.31.6 in /envs

Bumps [imageio](https://github.com/imageio/imageio) from 2.31.5 to 2.31.6.
- [Release notes](https://github.com/imageio/imageio/releases)
- [Changelog](https://github.com/imageio/imageio/blob/master/CHANGELOG.md)
- [Commits](imageio/imageio@v2.31.5...v2.31.6)

---
updated-dependencies:
- dependency-name: imageio
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

envs/requirements.txt

@@ -11,7 +11,7 @@ fonttools==4.43.1
 future==0.18.3
 idna==3.4
 imagecodecs==2023.9.18
-imageio==2.31.5
+imageio==2.31.6
 importlib-metadata==6.8.0
 importlib-resources==6.1.0
 itk==5.3.0