Fix 2146: use BFS algorithm for shortest path

[deanmalmgren]

• Closes Dynamic contexts, currency conversion, and failing to find the shortest path #2146 (insert issue number)
• Executed pre-commit run --all-files with no errors
• The change is fully covered by automated unit tests
• Documented in docs/ as appropriate -- NOT NEEDED
• Added an entry to the CHANGES file

I've tried to use the pre-commit hooks, but it was complaining about code that was not in my changeset. It seems like some issues leaked into the master branch.

[deanmalmgren]

@hgrecco is there anything else you need me to take care of as a part of this PR?

[hgrecco]

It looks good to me. I will merge it in this upcoming days if there are no showstopeers! Thanks.

[deanmalmgren]

@hgrecco not sure why the codspeed-benchmarks couldn't find pytest in the environment. Is there another patch PR that I can merge in that fixes this as I'm sure it'll be affecting other things. I'm wondering what else I can do to get this over the line...

[hgrecco]

@deanmalmgren Sorry for the long delay. Thanks a lot for the PR, it will be included in next pint version (scheduled for mid april)

[deanmalmgren]

No apologies necessary. I know how challenging it can be to manage an open source project on top of everything else. Appreciate you. If there's anything else I can do, let me know.

[hgrecco]

Just keep the great ideas and PR coming!