fac587ea07 ci: Use C++23 once for testing (MarcoFalke)
fa053ab7c0 build: Add Centos Stream 9 EOL URL (MarcoFalke)
Pull request description:
There are no plans to switch to C++23 anytime soon in the next couple of years. The only place right now that is known to benefit is `src/compat/byteswap.h`.
However, it is still useful to test with the option, because deprecated, removed or changed language features, as well as compiler changes that are guarded by the language version will be tested and developers can learn about them upfront.
Also includes a minor doc fixup commit.
ACKs for top commit:
davidgumberg:
ACK fac587ea07
TheCharlatan:
ACK fac587ea07
Tree-SHA512: 1b81788eb5b4da77715d8b047279de65ae6b8920d5a21fd8cc94c3b0edb588ab8ffb7eaffb2f8b7806045de1d47ca85ca629f49038eca762f3136bf380cf3c87
d08bedd81f