Bump shapely from 1.6.4.post2 to 1.7.0 in /cvat/requirements (#1709)

Bumps [shapely](https://github.com/Toblerity/Shapely) from 1.6.4.post2 to 1.7.0.
- [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/1.6.4.post2...1.7.0)

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

@@ -31,7 +31,7 @@ Markdown==3.2.2
 djangorestframework==3.9.3
 Pygments==2.6.1
 drf-yasg==1.17.0
-Shapely==1.6.4.post2
+Shapely==1.7.0
 pdf2image==1.6.0
 pascal_voc_writer==0.1.4
 django-rest-auth[with_social]==0.9.5