Bump snakeviz from 0.4.2 to 2.1.0 in /cvat/requirements (#1691)

Bumps [snakeviz](https://github.com/jiffyclub/snakeviz) from 0.4.2 to 2.1.0.
- [Release notes](https://github.com/jiffyclub/snakeviz/releases)
- [Changelog](https://github.com/jiffyclub/snakeviz/blob/master/CHANGES.rst)
- [Commits](https://github.com/jiffyclub/snakeviz/commits)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

cvat/requirements/development.txt

@@ -10,4 +10,4 @@ rope==0.11
 wrapt==1.12.1
 django-extensions==2.0.6
 Werkzeug==0.15.3
-snakeviz==0.4.2
+snakeviz==2.1.0