fix: version fall back when package metadata is unavailable

[adamcik]

I'm running things with nix these days, which runs without git, which means version might fail. In that case it is better to fallback to a dummy version IMO.

[jodal]

I think we could consider removing __version__ from all of our packages. importlib.metadata.version() is the right way to look up a package version in 2026.

[adamcik]

Sure, but the problem I had is that if that is pulling from git, and we have code that calls version I get in trouble. As typically I'll setup nix flake check which then runs pytest or whatever else in a hermetic env with just minimal deps and no copy of .git.

But if version() was only being called here and nowhere else it effectively solves the problem for me