RawSpeed submodule update (fix windows MSYS builds)

* Finally bump to C++20
* Use C++17's aligned `new` instead of `aligned_alloc()` / `_aligned_malloc()`
* Many code cleanups
* Fix `cameras.xml` XSD, make it verify with libxml2 2.12.0
* Drop obsolete workarounds for older toolchains
* Fix build on clang/i386 (on openSUSE Tumbleweed)
* Canon EOS 77D: improve black/white levels