Bump tensorboardx from 2.6.2.2 to 2.6.4

Bumps [tensorboardx](https://github.com/lanpa/tensorboardX) from 2.6.2.2 to 2.6.4.
- [Release notes](https://github.com/lanpa/tensorboardX/releases)
- [Changelog](https://github.com/lanpa/tensorboardX/blob/master/HISTORY.rst)
- [Commits](https://github.com/lanpa/tensorboardX/commits)

---
updated-dependencies:
- dependency-name: tensorboardx
  dependency-version: 2.6.4
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

requirements.txt

@@ -13,7 +13,7 @@ pytorch-pfn-extras==0.8.2
 scikit-image==0.25.2
 scikit-learn==1.6.1
 scipy==1.15.2
-tensorboardX==2.6.2.2
+tensorboardX==2.6.4
 torch==2.7.1
 torchvision==0.22.1
 tqdm==4.67.1