Bump rsa from 4.0 to 4.7

Bumps [rsa](https://github.com/sybrenstuvel/python-rsa) from 4.0 to 4.7.
- [Release notes](https://github.com/sybrenstuvel/python-rsa/releases)
- [Changelog](https://github.com/sybrenstuvel/python-rsa/blob/main/CHANGELOG.md)
- [Commits](sybrenstuvel/python-rsa@version-4.0...version-4.7)

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

Author: dependabot[bot]

requirements.txt

@@ -49,7 +49,7 @@ pytz==2019.3
 PyWavelets==1.1.1
 requests==2.18.4
 requests-oauthlib==1.3.0
-rsa==4.0
+rsa==4.7
 scikit-image==0.16.2
 scikit-learn==0.22.1
 scipy==1.4.1