Slipcover

This release fixes none of the wheels on PyPI tagged as appropriate for Python 3.13.

This release:

- adds support for Python 3.13 (tested on 3.13.0a6; may not work on earlier versions);
- improves `pytest-fork` detection;

Thanks to adiroiban for the early work on Python 3.13 support;

This release:
- improves performance handling subprocesses (Unix only);
- fixes a bug reporting subprocess data merge errors if tests close stderr;
- fixes a bug not passing the script name as a string in sys.argv[0] when executing a script directly;
- fixes a bug attempting to print coverage when none was collected;

This release adds `--merge`, which merges JSON coverage files, as in:


slipcover --merge a.json b.json --out c.json


Closes 12.

This release:
- adds [pytest-forked](https://github.com/pytest-dev/pytest-forked) support on Unix/MacOS;
- makes file matching more reliable and fixes bugs around matching relative paths;

Thanks to peterjc and P403n1x87 for their contributions!

This release:
- adds a "show_contexts" field to the JSON coverage output, improving compatibility with `coverage.py` and codecov;
- works around a rare issue reading source code when it contains non-ASCII characters;

Thank you, guillaumeLepape, for figuring out the Codecov issue and providing a fix.