chunksync: 0.3 -> 0.4

Semi-automatic update generated by https://github.com/ryantm/nix-update tools. These checks were done:

- built on NixOS
- ran `/nix/store/bgpzi08y1w7zgv0iaisdd974mdy6pdpl-chunksync-0.4/bin/chunksync -h` got 0 exit code
- ran `/nix/store/bgpzi08y1w7zgv0iaisdd974mdy6pdpl-chunksync-0.4/bin/chunksync -V` and found version 0.4
- ran `/nix/store/bgpzi08y1w7zgv0iaisdd974mdy6pdpl-chunksync-0.4/bin/chunksync -h` and found version 0.4
- found 0.4 with grep in /nix/store/bgpzi08y1w7zgv0iaisdd974mdy6pdpl-chunksync-0.4
- found 0.4 in filename of file in /nix/store/bgpzi08y1w7zgv0iaisdd974mdy6pdpl-chunksync-0.4