librealsense: 2.11.1 -> 2.12.0

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

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

These checks were done:

- built on NixOS

- 0 of 0 passed binary check by having a zero exit code.
- 0 of 0 passed binary check by having the new version present in output.
- found 2.12.0 with grep in /nix/store/px6ccyxxnyw1xklds9kcw8j2zdls3ays-librealsense-2.12.0
- directory tree listing: https://gist.github.com/e1d2253d92ab8f4bd8aa06a2fd223431
- du listing: https://gist.github.com/bafbf4e97cf5ec6f4471c2fe5f3d785a