Issue with json-c and Python 3.6 builds

[mauzey1]

Recent CircleCI workflows have failed when building CMOR for Python 3.6. The builds are giving the following errors.

Linux:

checking for json_object_new_object in -ljson-c... no
configure: error: Could not get a working json-c

OSX:

checking for Fortran libraries of ... 
checking for json_object_new_object in -ljson-c... no
configure: error: Could not get a working json-c

I will investigate why the json-c library is not working correctly with the Python 3.6 builds.

[mauzey1]

Here is a possibly relevant announcement by conda-forge. https://conda-forge.org/docs/user/announcements.html

2021-10-04
python 3.6 is now dropped when building conda-forge packages

python 3.6 is end-of-life in December 2021 and we are dropping support for it early to 
avoid having to rebuild packages as part of python 3.10 migration as that would save 
lots of CI resources.

[durack1]

Thanks for digging through this @mauzey1, I think let's wrap up dropping Python 3.6 support in the next release, pointing to this conda-forge announcement in the release notes