Add structured version info for pyexpat

Feature or enhancement

pyexpat.EXPAT_VERSION (from XML_ExpatVersion()) and pyexpat.version_info (from XML_ExpatVersionInfo()) describe the Expat library loaded at runtime: both functions are compiled into libexpat from its XML_MAJOR_VERSION, XML_MINOR_VERSION and XML_MICRO_VERSION macros. The same macros evaluated in pyexpat.c give the version of the headers the module was built against, which is what the #if XML_COMBINED_VERSION >= ... checks in the module depend on. The two can differ when a system libexpat is used. The build-time version is not exposed to Python; it can only be inferred from which parser methods exist.

Add pyexpat.VERSION_INFO for the build-time version, and make pyexpat.version_info a named tuple.

Linked PRs

• gh-157474

從 pyexpat.c 開始，這裡公開了 Expat 版本巨集和執行階段版本 API。追蹤現有的 VERSION_INFO 和 version_info 定義，然後驗證建置時版本是否被分開公開，以及 version_info 是否具有具名元組行為。如果有 pyexpat API 測試，請檢查這些測試，並確認當兩個版本不同時，它們都能被正確回報。