multimedia/*pipe-viewer: Update to 0.4.6

• Add FORK_MANAGER option
• Remove GTK3_USES=desktop-file-utils (.desktop file does not use MimeType)

ChangeLog: https://github.com/trizen/pipe-viewer/blob/0.4.6/Changes

• Fixed the internal extracting of streaming URLs.
• Extended fat32safe option to convert Unicode characters to ASCII equivalent when Text::Unidecode is available.
• Recognize several more audio itags.

PR: 271503, 269607