Allow durations without leading 0s in the hour

[mrob95]

Fixes pydantic/pydantic#8248

Supports the following formats:

>>> str(timedelta(hours=3))
'3:00:00'
>>> str(timedelta(minutes=3))
'0:03:00'
>>> str(timedelta(minutes=3, seconds=1))
'0:03:01'
>>> str(timedelta(days=3, hours=9, minutes=5, seconds=10))
'3 days, 9:05:10'

Note that this is technically a breaking change due to the change in error type when there are characters left over after parsing a duration, from InvalidCharTzSign to ExtraCharacters. I think this makes more sense as there is no such thing as a valid timezone for a duration.

I started down the road of trying to unify the time parsing between durations and times using PureTime, but it became a bit of a mess, requiring breaking changes to PureTime (e.g. PureTime stores hours as a u8 currently, but duration parsing needs at least u32).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.87%. Comparing base (0ffbcbb) to head (289c653).
Report is 11 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #74      +/-   ##
==========================================
- Coverage   99.12%   98.87%   -0.26%     
==========================================
  Files           6        6              
  Lines         917      975      +58     
==========================================
+ Hits          909      964      +55     
- Misses          8       11       +3     

Files with missing lines	Coverage Δ
src/duration.rs	99.04% <100.00%> (-0.96%)	⬇️

... and 4 files with indirect coverage changes

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[mrob95]

The CI pre-commit stage was failing trying to install pre-commit outside of a virtual environment. I copied the setup-python step from https://github.com/pydantic/pydantic-core/blob/main/.github/workflows/ci.yml#L265C1-L267C33 to fix.

[davidhewitt]

Thanks, I think the change in error message is probably positive 👍