databases/pgbackrest: Update to 2.47

https://github.com/pgbackrest/pgbackrest/releases/tag/release%2F2.47

Bug Fixes:

• Preserve block incremental info in manifest during delta backup.
• Fix block incremental file names in verify command.
• Fix spurious automatic delta backup on backup from standby.
• Skip recovery.signal for PostgreSQL >= 12 when recovery type=none.
• Fix unique label generation for diff/incr backup.
• Fix time-based archive expiration when no backups are expired.

Improvements:

• Improve performance of SFTP storage driver.
• Add timezone offset to info command date/time output.
• Centralize error handling for unsupported features.

Documentation Improvements:

• Clarify preference to install from packages in the user guide.

PR: 272735
Reported by: schoutm@gmail.com (maintainer)