Bump flower from 0.9.3 to 0.9.4

Bumps [flower](https://github.com/mher/flower) from 0.9.3 to 0.9.4.
- [Release notes](https://github.com/mher/flower/releases)
- [Changelog](https://github.com/mher/flower/blob/master/CHANGES)
- [Commits](https://github.com/mher/flower/compare/v0.9.3...v0.9.4)

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

setup.py

@@ -48,7 +48,7 @@ setup(
         'psycopg2-binary==2.8.4',
         'mgrs==1.3.6',
         'xmlunittest==0.5.0',
-        'flower==0.9.3',
+        'flower==0.9.4',
         'tqdm==4.45.0',
 	'requests==2.23.0',
     ],