Bump pillow from 6.1.0 to 7.1.0

Bumps [pillow](https://github.com/python-pillow/Pillow) from 6.1.0 to 7.1.0.
- [Release notes](https://github.com/python-pillow/Pillow/releases)
- [Changelog](https://github.com/python-pillow/Pillow/blob/master/CHANGES.rst)
- [Commits](https://github.com/python-pillow/Pillow/compare/6.1.0...7.1.0)

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

requirements.txt

@@ -10,7 +10,7 @@ repoze.lru==0.7
 rasterio==1.0.28
 attrs==19.1.0
 pyodm==1.5.4
-Pillow==6.1.0
+Pillow==7.1.0
 networkx==2.2
 scipy==1.5.4
 numpy==1.19.4