Bump xformers from 0.0.18 to 0.0.27.post2

Bumps [xformers](https://github.com/facebookresearch/xformers) from 0.0.18 to 0.0.27.post2.
- [Release notes](https://github.com/facebookresearch/xformers/releases)
- [Changelog](https://github.com/facebookresearch/xformers/blob/main/CHANGELOG.md)
- [Commits](facebookresearch/xformers@v0.0.18...v0.0.27.post2)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements.txt

@@ -13,7 +13,7 @@ tqdm
 --extra-index-url https://pypi.nvidia.com
 cuml-cu11==23.12.0
 dinov2==0.0.1.dev0
-xformers==0.0.18
+xformers==0.0.27.post2
 
 # --------- pytorch --------- #
 torch==2.0.0