Upgrade to latest pytest, cryptography & pyaml versions (#243)

Author: asherf

requirements-dev.txt

@@ -1,10 +1,10 @@
-PyYAML==5.4
+PyYAML==5.4.1
 cov-core==1.15.0
 coverage==5.5
 coveralls==1.5.1
-cryptography==3.3.2
+cryptography==3.4.7
 docopt==0.6.2
-pytest==6.2.2
+pytest==6.2.3
 pytest-cov==2.11.1
 -r requirements.txt
 -r requirements-rtd.txt