Fix issues when building OTIO in debug on Windows (and using Debug Python)

[cedrik-fuoco-adsk]

Link the Issue(s) this Pull Request is related to.

Fixes #1173

Summarize your change.

• Updated the Windows Debug library postfix to _d to match Python’s expected debug naming convention.
• Fixed pybind11 GIL assertion risk by lazily initializing _value_to_any (avoid constructing py::none() during static initialization) in otio_utils.cpp

Describe the reason for the change.

OpenRV builds OTIO from source to avoid compatibility issues with its custom Python distribution.
When pairing Debug OTIO with Debug Python on Windows, I ran into:

• A Debug-postfix mismatch (Python expects _d), which breaks resolution/loading of pyd.
• pybind11 GIL assertions caused by creating Python objects during static initialization (before the interpreter/GIL is guaranteed to be ready).

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: cedrik-fuoco-adsk / name: Cédrik Fuoco (38b0da1)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@5cb38bc). Learn more about missing BASE report.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1991   +/-   ##
=======================================
  Coverage        ?   85.15%           
=======================================
  Files           ?      181           
  Lines           ?    12783           
  Branches        ?     1206           
=======================================
  Hits            ?    10885           
  Misses          ?     1715           
  Partials        ?      183           

Flag	Coverage Δ
py-unittests	85.15% <100.00%> (?)

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Files with missing lines	Coverage Δ
...ntimelineio/opentimelineio-bindings/otio_utils.cpp	77.77% <100.00%> (ø)

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[JeanChristopheMorinPerso]

Interesting finding! We fixed a similar issue 4 years ago in #1070.