admin/doc-requirements: pin sphinx-autodoc-typehints to 1.10.3

admin/doc-requirements: pin sphinx-autodoc-typehints to 1.10.3

to silence following error:

ERROR: sphinx-autodoc-typehints 1.11.0 has requirement Sphinx>=3.0, but you'll have sphinx 2.4.3 which is incompatible.

* update breathe to the latest release, 4.14.2, which supports sphinx <
  3.0
* pin sphinx to 2.4.4 the last sphinx before 3.0.0. as if sphinx >= 3.0
is used, we have errors like:

Invalid C declaration: Expected identifier in nested name, got keyword: int [error at 18]
  CEPH_RADOS_API int rados_aio_append (rados_ioctx_t io, const char *oid, rados_completion_t completion, const char *buf, size_t len)
  ------------------^

Signed-off-by: Kefu Chai <kchai@redhat.com>