devel/py-maturin: Add missing dependency

• Since release 1.8.7, libzstd.so is also required, which was not noticed when bulk building/testing this port and its consumers with default options, because libzstd.so is automatically provided by lang/rust via its dependency on ftp/curl. The latter one supplies libzstd.so by default via the ZSTD option.

• Resolve the issue by adding the missing dependency to LIB_DEPENDS and bump PORTREVISION due changed dependencies.

PR: 287683
Reported by: Christos Chatzaras