openvdb: 5.0.0 -> 5.1.0

Semi-automatic update generated by https://github.com/ryantm/nixpkgs-update tools.

This update was made based on information from https://repology.org/metapackage/openvdb/versions.

These checks were done:

- built on NixOS
- Warning: no binary found that responded to help or version flags. (This warning appears even if the package isn't expected to have binaries.)
- found 5.1.0 with grep in /nix/store/firif9xzzgizin13337znminprn0h2g1-openvdb-5.1.0
- directory tree listing: https://gist.github.com/ab56d3a535f58829ccdfb0187ff9afed