libbson: 1.9.4 -> 1.9.5

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

This update was made based on information from https://repology.org/metapackage/libbson/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 1.9.5 with grep in /nix/store/lmn0g67a9wq9f8mg7v2afh111gmsbv6c-libbson-1.9.5
- directory tree listing: https://gist.github.com/ef0187572a2c4e53759a875695c4d6ea