Version 3.0.0 RC 2

This is another release candidate. See the changelog in the docs for the combined changelog; this is just the changes since RC 1:

• feat: scoped_critical_section by @henryiii in #5684
• fix(cmake): regression in include guard by @henryiii in #5691
• fix: don't destruct module objects in atexit by @b-pass in #5688
• fix: prepare for 3.14 beta 2 by @henryiii in #5697
• chore(cmake): add compile commands to preset by @henryiii in #5685
• chore: bump maximum clang tested to 20 by @henryiii in #5692
• chore: rename macro PYBIND11_SUBINTERPRETER_SUPPORT -> PYBIND11_HAS_SUBINTERPRETER_SUPPORT to meet naming convention by @XuehaiPan in #5682
• chore: use CPython macros to construct PYBIND11_VERSION_HEX by @XuehaiPan in #5683
• docs: more warnings about locking and the GIL by @henryiii in #5689
• docs: update contributing/release guide a little by @henryiii in #5681
• tests: always disable on the nogil build by @henryiii in #5701
• tests: expect free-threaded import warnings by @henryiii in #5680
• tests: skip some flaky gil tests on nogil by @henryiii in #5699

Full Changelog: v3.0.0rc1...v3.0.0rc2