Bump shapely from 1.7.0 to 1.7.1 in /cvat/requirements (#2064)

Bumps [shapely](https://github.com/Toblerity/Shapely) from 1.7.0 to 1.7.1.
- [Release notes](https://github.com/Toblerity/Shapely/releases)
- [Changelog](https://github.com/Toblerity/Shapely/blob/master/CHANGES.txt)
- [Commits](https://github.com/Toblerity/Shapely/compare/1.7.0...1.7.1)

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/base.txt

@@ -32,7 +32,7 @@ Markdown==3.2.2
 djangorestframework==3.11.1
 Pygments==2.6.1
 drf-yasg==1.17.1
-Shapely==1.7.0
+Shapely==1.7.1
 pdf2image==1.13.1
 pascal_voc_writer==0.1.4
 django-rest-auth[with_social]==0.9.5