remove rsa from constraints file

Author: daniel-sanche

testing/constraints-3.7.txt

@@ -7,7 +7,6 @@
 # Then this file should have foo==1.14.0
 pyasn1-modules==0.2.1
 setuptools==40.3.0
-rsa==3.1.4
 aiohttp==3.6.2
 requests==2.20.0
 pyjwt==2.0