fast_data: update for networkx 2.0

[jtniehof]

This is a small change to update the fast_data script to use the networkx 2.0 syntax. Earlier versions of 2.x permitted the old syntax, but this is gone now. networkx 2.0 (2017-09-20) is now the minimum version.

The fast_data script is the only thing that uses networkx and so this doesn't impact anybody not using it. Long-term, yes, it needs to be better integrated, tested, etc. but this stops the bleeding on one of my projects.

PR Checklist

• [X] Pull request has descriptive title
• [X] Pull request gives overview of changes
• [X] (N/A) New code has inline comments where necessary
• [X] (N/A) Any new modules, functions or classes have docstrings consistent with dbprocessing style
• [X] (N/A) Major new functionality has appropriate Sphinx documentation
• [X] (N/A) Added an entry to release notes if fixing a major bug or providing a major new feature
• [X] (N/A) New features and bug fixes should have unit tests
• [X] (N/A) Relevant issues are linked in the description (use Closes # if this PR closes the issue, or some other reference, such as See # if it is related in some other way)

[jtniehof]

Ugh, the CI is completely broken now. Rather than trying to update the CircleCI config I'm strongly considering just porting to GitHub Actions. That's what we're using on SpacePy and I'm becoming much more adept with it. It doesn't have the nice "ssh into the runner" feature, unfortunately, but would be a path to solving #53 and #76. @dnadeau-lanl , thoughts?

EDIT: Got things kicked off again (this was, I think, a legacy of cleanup from a github security issue) but now the python3 unit tests are tripping up on the sqlalchemy syntax with new sqlalchemy. 1.4 came out in March 2021 so it's probably time to just move to the new syntax wholesale and require 1.4.

[dnadeau-lanl]

Jon, I agree with you that we could port to github Actions. SSH is a nice feeture to have but not mandatory and if helps you solving 2 issues, go for it!

Updating SQLAlchemy seems to be a must after 2 yers. :-)

[jtniehof]

Thanks. I think my route forward then is the sqlalchemy fix, this PR, and then I'll port to GHA.

[jtniehof]

@dnadeau-lanl : this is ready to go now that #136 is in, thanks!