version: replace manual ASCII checks with isprint() for clarity

version: replace manual ASCII checks with isprint() for clarity

Since the isprint() function checks for printable characters, let's
replace the existing hardcoded ASCII checks with it. However, since
the original checks also handled spaces, we need to account for spaces
explicitly in the new check.

Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Usman Akinyemi <usmanakinyemi202@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>