help2man: Update to 1.48.1

Changelog:
Version 1.48            February 6, 2021

  * Add Serbian, Swedish, Brazilian Portuguese and Chinese (simplified)
    translations of info documentation.
  * Add Tamil and Chinese (simplified) translations.
  * Move table of contents to the top of the texi file so that it appears
    in the correct location in the html page.
  * Use the package name and version as the default for --source (was
    program).
  * Support packages in version strings without the GNU or Free prefix.
  * Allow an optional second dash to separate the package name from the
    version for multi-word packages: "program - package name - version".
  * Suppress creation of an empty pkglibdir when nls is disabled.
  * Fix ordering of "other" sections in manual page.
  * Use POSIX compliant TZ when setting UTC (thanks to Paul Eggert).

(ryoon)