gtexinfo: update to 7.0.3.

7.0.3 (26 March 2023)
This is a bug-fix release with minimal changes.

* texi2any
  . fix performance regression when Perl binary extension (XS) modules
    are not being used (e.g. with TEXINFO_XS=omit)

* info
  . further fix of recoding of UTF-8 files to ASCII to avoid text
    disappearing from nodes
  . avoid possible freeze at start of a file with `-v nodeline=pointers'

(wiz)