Version 2.9.0

This is the last version to support Python 2.7 and 3.5.

New Features:

• Allow py::args to be followed by other arguments; the remaining arguments are implicitly keyword-only, as if a py::kw_only{} annotation had been used. #3402

Changes:

• Make str/bytes/memoryview more interoperable with std::string_view. #3521
• Replace _ with const_name in internals, avoid defining pybind::_ if _ defined as macro (common gettext usage) #3423

Bug fixes:

• Fix a rare warning about extra copy in an Eigen constructor. #3486
• Fix caching of the C++ overrides. #3465
• Add missing std::forward calls to some cpp_function overloads. #3443
• Support PyPy 7.3.7 and the PyPy3.8 beta. Test python-3.11 on PRs with the python dev label. #3419
• Replace usage of deprecated Eigen::MappedSparseMatrix with Eigen::Map<Eigen::SparseMatrix<...>> for Eigen 3.3+. #3499
• Tweaks to support Microsoft Visual Studio 2022. #3497

Build system improvements:

• Nicer CMake printout and IDE organisation for pybind11's own tests. #3479
• CMake: report version type as part of the version string to avoid a spurious space in the package status message. #3472
• Flags starting with -g in $CFLAGS and $CPPFLAGS are no longer overridden by .Pybind11Extension. #3436
• Ensure ThreadPool is closed in setup_helpers. #3548
• Avoid LTS on mips64 and ppc64le (reported broken). #3557