Add source in release

[blegat]

The PyPI tarball is missing the vroom C++ submodule files (bind/_main.cpp, etc.). When someone builds from source, it fails immediately. This fixes it by including submodule content in the sdist.
One example is Mac OS 14.5. Since we target Mac OS 15, users of that older Mac OS version won't have any binary and hence it will try to build from source but it won't find ``bind/_main.cpp` and then error.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 79.5%. Comparing base (8432ae4) to head (21238df).

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #136   +/-   ##
=====================================
  Coverage   79.5%   79.5%           
=====================================
  Files         29      29           
  Lines       1902    1902           
  Branches     149     149           
=====================================
  Hits        1513    1513           
  Misses       377     377           
  Partials      12      12           

Flag	Coverage Δ
binding	71.7% <ø> (ø)
python	92.1% <ø> (ø)

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

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.