maint: add PyPY check in CI

Author: oscarbenjamin

.github/workflows/buildwheel.yml

@@ -109,7 +109,7 @@ jobs:
         os: [ubuntu-20.04, windows-2019, macos-13, macos-14]
         # This list to be kept in sync with cibuildwheel config
         # and python-requires in pyproject.toml.
-        python-version: ['3.10', '3.11', '3.12', '3.13-dev']
+        python-version: ['3.10', '3.11', '3.12', '3.13-dev', 'pypy3.10']
 
     steps:
       - uses: actions/setup-python@v5

pyproject.toml

@@ -58,7 +58,7 @@ package = "flint"
 [tool.cibuildwheel]
 # requires-python needs to keep in sync with this and also the list of Python
 # versions the wheels are tested against in CI.
-build = "cp310-* cp311-* cp312-* cp313-*"
+build = "cp310-* cp311-* cp312-* cp313-* pp310-*"
 skip = "*-win32 *-manylinux_i686 *-musllinux_*"
 
 # This is needed for free-threaded wheels: