pyyaml is not installed when installing cftdeploy

[Joel Haubold]

I use pipx to manage cli utilities in python.

After installing pipx install cftdeploy then cfn-validate fails

$ cft-validate
Traceback (most recent call last):
  File "/Users/jhaubold/.local/bin/cft-validate", line 5, in <module>
    from cftdeploy import cft_validate
  File "/Users/jhaubold/.local/pipx/venvs/cftdeploy/lib/python3.7/site-packages/cftdeploy/__init__.py", line 1, in <module>
    from .manifest import *
  File "/Users/jhaubold/.local/pipx/venvs/cftdeploy/lib/python3.7/site-packages/cftdeploy/manifest.py", line 1, in <module>
    from .template import *
  File "/Users/jhaubold/.local/pipx/venvs/cftdeploy/lib/python3.7/site-packages/cftdeploy/template.py", line 7, in <module>
    import yaml
ModuleNotFoundError: No module named 'yaml'

Installing pyyaml into the virtual env for cftdeploy solves this error

$ pipx runpip cftdeploy install pyyaml