docs: prepare for 2.13.2 (#5299)

* docs: prepare for 2.13.2

Signed-off-by: Henry Schreiner <[email protected]>

* Update changelog.rst

* Update changelog.rst

---------

Signed-off-by: Henry Schreiner <[email protected]>

Author: henryiii

docs/changelog.rst

@@ -15,6 +15,64 @@ IN DEVELOPMENT
 
 Changes will be summarized here periodically.
 
+New Features:
+
+* Support for Python 3.7 was removed. (Official end-of-life: 2023-06-27).
+  `#5191 <https://github.com/pybind/pybind11/pull/5191>`_
+
+Support for CMake older than 3.15 and some older compilers will also be removed.
+
+Version 2.13.2 (August 13, 2024)
+--------------------------------
+
+New Features:
+
+* A ``pybind11::detail::type_caster_std_function_specializations`` feature was added, to support specializations for
+  ``std::function``'s with return types that require custom to-Python conversion behavior (to primary use case is to catch and
+  convert exceptions).
+  `#4597 <https://github.com/pybind/pybind11/pull/4597>`_
+
+
+Changes:
+
+
+* Use ``PyMutex`` instead of ``std::mutex`` for internal locking in the free-threaded build.
+  `#5219 <https://github.com/pybind/pybind11/pull/5219>`_
+
+* Add a special type annotation for C++ empty tuple.
+  `#5214 <https://github.com/pybind/pybind11/pull/5214>`_
+
+* When compiling for WebAssembly, add the required exception flags (CMake 3.13+).
+  `#5298 <https://github.com/pybind/pybind11/pull/5298>`_
+
+Bug fixes:
+
+* Make ``gil_safe_call_once_and_store`` thread-safe in free-threaded CPython.
+  `#5246 <https://github.com/pybind/pybind11/pull/5246>`_
+
+* A missing ``#include <algorithm>`` in pybind11/typing.h was added to fix build errors (in case user code does not already depend
+  on that include).
+  `#5208 <https://github.com/pybind/pybind11/pull/5208>`_
+
+* Fix regression introduced in #5201 for GCC<10.3 in C++20 mode.
+  `#5205 <https://github.com/pybind/pybind11/pull/5205>`_
+
+
+.. fix(cmake)
+
+* Remove extra = when assigning flto value in the case for Clang in CMake.
+  `#5207 <https://github.com/pybind/pybind11/pull/5207>`_
+
+
+Tests:
+
+* Adding WASM testing to our CI (Pyodide / Emscripten via scikit-build-core).
+  `#4745 <https://github.com/pybind/pybind11/pull/4745>`_
+
+* clang-tidy (in GitHub Actions) was updated from clang 15 to clang 18.
+  `#5272 <https://github.com/pybind/pybind11/pull/5272>`_
+
+
 Version 2.13.1 (June 26, 2024)
 ------------------------------