Update version specifier

[fabaff]

gradient-cli/setup.py

Line 70 in 9eb645e

'PyYAML==5.*',

is no longer a valid version specifier.

error in gradient setup command: 'install_requires' must be a string or list of strings containing valid project/version requirement specifiers; Expected end or semicolon (after version specifier)
    PyYAML>=5.*
          ~~~^

Affects also websocket-client==0.57.*