use pycryptodome instead of pycrypto

HISTORY.rst

@@ -7,6 +7,7 @@ Release History
 ------------------
 
 - When a request fails due to EAGAIN response, retry with exp backoff up to 20 seconds.
+- Replace pycrypto dependency with pycryptodome.
 
 
 1.0.0 (2019-10-31)

requirements.txt

 requests>=0.10
-pycrypto
+pycryptodome>=3.9.1,<4.0.0
 pathlib==1.0.1
 tenacity>=5.1.5,<6.0.0