wxSVG: 1.5.11 -> 1.5.13

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. 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 1.5.13 with grep in /nix/store/hcf1ibw1hvrwic1zagy3cvi1fc73rfgk-wxSVG-1.5.13
- found 1.5.13 in filename of file in /nix/store/hcf1ibw1hvrwic1zagy3cvi1fc73rfgk-wxSVG-1.5.13