devel/libdatovka: Update 0.7.0 => 0.7.1, improve port

Changelog:
https://gitlab.nic.cz/datovka/libdatovka/-/blob/v0.7.1/ChangeLog

Improve port:

• fix dependencies;
• remove GNU_CONFIGURE_MANPREFIX.

PR: 285768
Co-authored-by: Martin Filla <freebsd@sysctl.cz> (maintainer)