gtkdatabox: 0.9.2.0 -> 0.9.3.0

Semi-automatic update. 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 0.9.3.0 with grep in /nix/store/3axd91hc3vi45w0j8yw0qfgwip4cx9da-gtkdatabox-0.9.3.0
- found 0.9.3.0 in filename of file in /nix/store/3axd91hc3vi45w0j8yw0qfgwip4cx9da-gtkdatabox-0.9.3.0