Documentation: Update news.rst

[reneme]

This updates the release notes for all patches added since Botan 3.2.0. The PRs and commits below seemed purely internal and not warranting a mention. Everything else should be accounted for. @randombit please feel free to pull this and adapt at will.

• Use variable to refer to Emscripten when linking #3854

• BufferSlicer::take<count>() & BufferStuffer::next<bytes>() #3856

• Move const time memory comparison utils to ct_utils.h #3760

• FIX: explicitly specify the make tool in mingw build #3781

• CI: ci_build.py selects sane defaults when run on Windows #3779

• Update docstring of draft-irtf-cfrg-hash-to-curve #3831

• examples target should require boost #3787

• Add sig algos and key agreements to bench.py #3829

• Don't inline Null_RNG::fill_bytes_with_input

• Remove abort call accidentally left over from debugging

[coveralls]

coverage: 92.002% (+0.006%) from 91.996%
when pulling 0688d06 on doc/update_news
into 7f15ce7 on master.

[randombit]

Thanks so much