[CI] Update CI workflow

[bryanwweber]

Changes proposed in this pull request

• Version bumps of dependencies in the CI workflow
• Fix location of Boost libraries on Windows
• Add tests on Python 3.9 and Ubuntu 20.04
• Add format specification in Pdep error printout

If applicable, fill in the issue number this pull request is fixing

Fixes #944

Checklist

• There is a clear use-case for this code change
• The commit message has a short title & references relevant issues
• Build passes (scons build & scons test) and unit tests address code coverage
• The pull request is ready for review

[ischoegl]

#944 is still there ... no idea what’s causing that.

[bryanwweber]

Yeah, seems to be something specific to the Conda-Forge SUNDIALS installations. Probably have to debug it locally.

On the plus side, no problems with Python 3.9!

[speth]

I opened #947 to fix #944, but didn't realize that there were other things breaking the CI. I think adding my commit from that PR to this one should put us back into business.

[bryanwweber]

There are some changes here which are also in 68dee92 in #641. Presumably #641 will need to be rebased to drop the commit I pushed to Gandhali's branch once this is merged.

[ischoegl]

🎉 ... looks like CI is back! Are there any other updates planned under this PR?

[bryanwweber]

No, I think this is ready to merge!

[ischoegl]

👍 ... Excellent - I rebased #949 (which is a trivial fix), #936/#931/#907 (which should be ready after being reviewed by @speth last weekend again), and #921 (not sure about the eventual fate). I don't have any other plans for the moment (I'll still fix trivial issues if they come up and pique my interest - especially if they are based on things I implemented over the last 1 1/2 years).