Improve typing of the drop_frame parameter on the RationalTime.to_timecode method

[JeanChristopheMorinPerso]

Summarize your change.

A couple of months ago, I noticed that the drop_frame parameter of the RationalTime.to_timecode method was using py::object as its type. This is confusing for the user.

With the change, running help(opentimelineio.opentime.RationalTime.to_timecode) returns:

to_timecode(...)
    to_timecode(*args, **kwargs)
    Overloaded function.
    
    1. to_timecode(self: opentimelineio._opentime.RationalTime, rate: float, drop_frame: Optional[bool]) -> str

And it still works as before:

>>> opentimelineio.opentime.RationalTime(30 * 59 + 30).to_timecode(29.97, 0)
'00:29:58:06'
>>> opentimelineio.opentime.RationalTime(30 * 59 + 30).to_timecode(29.97, False)
'00:29:58:06'
>>> opentimelineio.opentime.RationalTime(30 * 59 + 30).to_timecode(29.97, 1)
'00:30:00;00'
>>> opentimelineio.opentime.RationalTime(30 * 59 + 30).to_timecode(29.97, True)
'00:30:00;00'
>>> opentimelineio.opentime.RationalTime(30 * 59 + 30).to_timecode(29.97, None)
'00:30:00;00'

[codecov-commenter]

Codecov Report

Merging #1443 (b0d5ce4) into main (21970b8) will decrease coverage by 1.70%.
The diff coverage is 100.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1443      +/-   ##
==========================================
- Coverage   86.38%   84.67%   -1.71%     
==========================================
  Files         201      203       +2     
  Lines       20854    22547    +1693     
  Branches     2298     4530    +2232     
==========================================
+ Hits        18014    19092    +1078     
- Misses       2244     2396     +152     
- Partials      596     1059     +463     

Flag	Coverage Δ
py-unittests	84.67% <100.00%> (-1.71%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...pentimelineio/opentimelineio-bindings/otio_utils.h	75.28% <ø> (-1.19%)	⬇️
...lineio/opentime-bindings/opentime_rationalTime.cpp	95.49% <100.00%> (+1.66%)	⬆️
...entimelineio-bindings/otio_serializableObjects.cpp	53.79% <0.00%> (-37.79%)	⬇️
...eio/opentimelineio-bindings/otio_anyDictionary.cpp	70.58% <0.00%> (-29.42%)	⬇️
...elineio/opentimelineio-bindings/otio_anyVector.cpp	72.22% <0.00%> (-27.78%)	⬇️
...ntimelineio/opentimelineio-bindings/otio_tests.cpp	50.37% <0.00%> (-20.05%)	⬇️
src/opentimelineio/typeRegistry.h	81.25% <0.00%> (-18.75%)	⬇️
src/opentimelineio/composition.h	70.37% <0.00%> (-18.52%)	⬇️
...ntimelineio/opentimelineio-bindings/otio_imath.cpp	45.79% <0.00%> (-15.75%)	⬇️
src/opentimelineio/track.cpp	80.14% <0.00%> (-11.16%)	⬇️
... and 50 more

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[ssteinbach]

Looks pretty good, just wanted to make sure that I understand the new header and how it ties into this change.