www/gitea: Update 1.25.4 => 1.25.5

While here, specify minimum Go version since in 2026Q1
Go default is 1.24 and gitea requires minimum 1.25.

Release notes:
https://blog.gitea.com/release-of-1.25.5/

Changelog:
https://github.com/go-gitea/gitea/releases/tag/v1.25.5

PR: 293986
Reported by: ports@foss-daily.org (maintainer)
Approved by: maintainer, vvd (mentor)
MFH: 2026Q1

(cherry picked from commit 84595ff66fad03b7d4e8e872acdf7753acfbdc88)