security/doas: update to 6.3p12

6.3p11:

• Cleaned up error checking for temporary files, removed redundant check.
• Fixed status check for copy and editor launch.

6.3p12:

• Make sure doasedit can work when target file to edit has a leading slash

character. ie A full path name is used.

• Update doas.1 manual page to indicate problems with piping input

on Linux when processes are launched by doas.

Upstream release announcement:
https://github.com/slicer69/doas/releases/tag/6.3p11
https://github.com/slicer69/doas/releases/tag/6.3p12

PR: 278897
MFH: 2024Q2
(cherry picked from commit e05da69d0d3fc274c73a0fbc4f312da3b9265b90)