Update tensorboard version to fix deadlock (#7435)

Fixes #7434


### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).
- [ ] Breaking change (fix or new feature that would cause existing
functionality to change).
- [ ] New tests added to cover the changes.
- [ ] Integration tests passed locally by running `./runtests.sh -f -u
--net --coverage`.
- [ ] Quick tests passed locally by running `./runtests.sh --quick
--unittests --disttests`.
- [ ] In-line docstrings updated.
- [ ] Documentation updated, tested `make html` command in the `docs/`
folder.

Signed-off-by: YunLiu <[email protected]>
Co-authored-by: Mingxin Zheng <[email protected]>

requirements-dev.txt

@@ -6,7 +6,7 @@ scipy>=1.7.1
 itk>=5.2
 nibabel
 pillow!=8.3.0  # https://github.com/python-pillow/Pillow/issues/5571
-tensorboard>=2.6  # https://github.com/Project-MONAI/MONAI/issues/5776
+tensorboard>=2.12.0  # https://github.com/Project-MONAI/MONAI/issues/7434
 scikit-image>=0.19.0
 tqdm>=4.47.0
 lmdb