chore: build free-threading wheels

Author: Rogdham

.github/workflows/build.yml

@@ -13,9 +13,9 @@ on:
 env:
   PYTHON_VER: "3.11" # Python to run test/cibuildwheel
   CIBW_BUILD: >
-    cp310-* cp311-* cp312-* cp313-* cp314-*
+    cp310-* cp311-* cp312-* cp313-* cp313t-* cp314-* cp314t-*
     pp310-* pp311-*
-  CIBW_ENABLE: pypy pypy-eol
+  CIBW_ENABLE: cpython-freethreading pypy pypy-eol
   CIBW_TEST_COMMAND: python -m unittest discover {project}/tests
 
 jobs:

CHANGELOG.md

@@ -9,6 +9,7 @@ All notable changes to this project will be documented in this file.
 ## 0.18.0 (October 5, 2025)
 
 - Support for Python 3.14
+- Build free-threaded wheels for CPython 3.13 and 3.14, even if the feature is not supported
 - Deprecate the `read_size` and `write_size` parameters of `ZstdFile` and `SeekableZstdFile`
 - Deprecate `richmem_compress` and `RichMemZstdCompressor`
 - Rework documentation to suggest using `compression.zstd` from Python stdlib, and provide a migration guide

src/bin_ext/pyzstd.c

@@ -579,6 +579,8 @@ _zstd_free(void *module)
 #ifdef USE_MULTI_PHASE_INIT
 static PyModuleDef_Slot _zstd_slots[] = {
     {Py_mod_exec, _zstd_exec},
+    // note: we do NOT support multiple interpreters
+    // note: we do NOT support free-threading
     {0}
 };
 #endif