Remove duplicate constraints

requirements/constraints.txt

@@ -124,17 +124,11 @@ vulture<2.0
 # sympy latest version causing test failures.
 sympy==1.6.2
 
-# cryptography 3.3.1 started failing tests on sandbox because it dropped support for python3.5
-cryptography==3.2.1
-
 # greater versions breaking the code
 Sphinx==3.3.0
 
 # latest edx-bulk-grades==0.8.5 is giving migration error.
 edx-bulk-grades<0.8.5
 
-# social-auth-core==4.3.0 requires PyJWT > 2.0.0
-social-auth-core<4.0.3
-
 # python3-saml==1.10.0 version started breaking a11y tests
 python3-saml<1.10.0