Installation of aswf-docker - yaml issue

To use the ASWF docker images, I installed the `aswf-docker` utility following the steps explained [here](https://github.com/AcademySoftwareFoundation/aswf-docker/blob/master/python/README.md). Even if it successfully installs the tool (i.e. `aswf-docker` is working fine), it reports an error around `yaml` during the installation:

1. git clone https://github.com/AcademySoftwareFoundation/aswf-docker
2. cd aswf-docker
3. python3 setup.py install

The installation is on `macOS 10.15.7` with `docker 20.10.7`

```
Installed /usr/local/lib/python3.9/site-packages/requests-2.23.0-py3.9.egg
Searching for pyyaml==5.3.1
Reading https://pypi.org/simple/pyyaml/
Downloading https://files.pythonhosted.org/packages/64/c2/b80047c7ac2478f9501676c988a5411ed5572f35d1beff9cae07d321512c/PyYAML-5.3.1.tar.gz#sha256=b8eac752c5e14d3eca0e6dd9199cd627518cb5ec06add0de9d32baeee6fe645d
Best match: PyYAML 5.3.1
Processing PyYAML-5.3.1.tar.gz
Writing /var/folders/bv/l130z2yj1h322ry0n1bhk6th0000gp/T/easy_install-affusizc/PyYAML-5.3.1/setup.cfg
Running PyYAML-5.3.1/setup.py -q bdist_egg --dist-dir /var/folders/bv/l130z2yj1h322ry0n1bhk6th0000gp/T/easy_install-affusizc/PyYAML-5.3.1/egg-dist-tmp-oxg38707
warning: the 'license_file' option is deprecated, use 'license_files' instead
In file included from ext/_yaml.c:596:
ext/_yaml.h:2:10: fatal error: 'yaml.h' file not found
#include
^~~~~~~~
1 error generated.
Error compiling module, falling back to pure Python
zip_safe flag not set; analyzing archive contents...
Copying PyYAML-5.3.1-py3.9-macosx-10.15-x86_64.egg to /usr/local/lib/python3.9/site-packages
Adding PyYAML 5.3.1 to easy-install.pth file
```

Start with python/README.md and the setup.py install command described in the issue, then reproduce the PyYAML 5.3.1 installation on the reported macOS and Python environment. Trace the dependency installation around the missing yaml.h message; done means the documented installation completes without reporting this YAML build error.

Written by the indexing model from the issue text.