Add ctypes 0.23.0

[yallop]

No description provided.

[avsm]

Some test failures that may be worth looking into:

# File "tests/test-oo_style/stub-generator/dune", line 21, characters 9-24:
# 21 |   (names generated_stubs))
#               ^^^^^^^^^^^^^^^
# (cd _build/default/tests/test-oo_style/stub-generator && /usr/sbin/gcc -O2 -fno-strict-aliasing -fwrapv -pthread -fPIC -D_FILE_OFFSET_BITS=64 -g -I /home/opam/.opam/4.14/lib/ocaml -I /home/opam/.opam/4.14/lib/bigarray-compat -I /home/opam/.opam/4.14/lib/ctypes -I /home/opam/.opam/4.14/lib/integers -I /home/opam/.opam/4.14/lib/stdlib-shims -I ../../clib -o generated_stubs.o -c generated_stubs.c)
# generated_stubs.c: In function ‘cstubs_tests_2_new_chorse’:
# generated_stubs.c:14:25: error: initialization of ‘struct animal *’ from incompatible pointer type ‘struct chorse *’ [-Wincompatible-pointer-types]
#    14 |    struct animal* x10 = new_chorse(x7);
#       |                         ^~~~~~~~~~

[yallop]

The failure (also reported in yallop/ocaml-ctypes#784) appears to be a result of recent gcc releases turning what was previously a warning into an error. It's only a test failure, not a problem in library code. There's a fix in yallop/ocaml-ctypes#785 that'll be in the next ctypes release.

[avsm]

Thanks! You may want to announce this on https://discuss.ocaml.org, where we have a Community category and an announce tag for this purpose.