Improve error handling

[ChristopherRabotin]

There are currently a few spots in the code where we check that the input f64 is finite. If not, the function will panic (on purpose).

This is potentially catastrophic for flight critical systems. Instead, the code should return a Result for all of the functions that may fail.

Moreover, when using the epoch formatter, the errors should be incredibly clear, similarly to how good the errors are in rustc. It seems that the snafu library could handle this pretty well, so I should explore using snafu. Snafu supports no-std environments, even with Backtraces, so it may be worth using it instead of thiserror which is std-only.

Cf. kube-rs/kube#453

[ChristopherRabotin]

This should include exporting the exception types to Python so that they can be caught without a bare exception (this upsets ruff).

[ChristopherRabotin]

I can't seem to figure out how to derive from BaseException. As such, the "fix" for the Python bare exception ruff error is simply to not use a bare exception and use except Exception as e instead (which is not in fact a bare exception).

Cf. PyO3/pyo3#4165