bpo-26219: Fix compiler warning in _PyCode_InitOpcache() (GH-13997) (GH-14000)

Fix MSVC warning:

    objects\codeobject.c(285): warning C4244: '=':
    conversion from 'Py_ssize_t' to 'unsigned char',
    possible loss of data
(cherry picked from commit 376ce9852eec4e97745c723f0dd0fe64383c6cd3)

Co-authored-by: Victor Stinner <vstinner@redhat.com>
1 file changed