Bump mgrs from 1.3.7 to 1.3.8 (#130)

Bumps [mgrs](https://github.com/hobu/mgrs) from 1.3.7 to 1.3.8.
- [Release notes](https://github.com/hobu/mgrs/releases)
- [Commits](https://github.com/hobu/mgrs/compare/1.3.7...1.3.8)

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

setup.py

@@ -46,7 +46,7 @@ setup(
         'shapely==1.7.1',
         'ogn-client==0.9.7',
         'psycopg2-binary==2.8.5',
-        'mgrs==1.3.7',
+        'mgrs==1.3.8',
         'xmlunittest==0.5.0',
         'flower==0.9.5',
         'tqdm==4.48.2',