[$] Getting extensions to work with free-threaded Python

One of the biggest changes to come to the Python world is the addition of the free-threading
interpreter, which eliminates the global
interpreter lock (GIL) that kept the interpreter thread-safe, but also
serialized multi-threaded Python code. Over the years, the GIL has been a
source of complaints about the scalability of Python code using
threads, so many developers have been looking forward to the change, which
has been an experimental feature since Python 3.13
was released in October 2024. Making the free-threaded version work
with the rest of the Python ecosystem, especially native extensions, is an
ongoing effort, however; Nathan Goldbaum and Lysandros Nikolaou spoke at PyCon US 2025 about those efforts.