Update pytest version to remove py dependency

Dependabot flagged 'py' as being vulnerable to a DoS. It likely doesn't affect us, but the recommendation is that 'pytest' removed dependency on 'py' in 7.2.0 so let's do that. 

This is discussed in a thread found here: pytest-dev/py#287 (comment)

python-client/requirements.txt

@@ -16,7 +16,7 @@ py==1.11.0
 pyasn1==0.4.8
 pyasn1-modules==0.2.8
 pyparsing==3.0.7
-pytest==6.2.5
+pytest==7.2.0
 requests==2.31.0
 rsa==4.8
 six==1.15.0