Fails to build with Rust >=1.73

Hi, We have removed (hopefully temporary) `gobang` from our (NetBSD) package tree, as it doesn't build with Rust-1.73. [The reason](http://shadow.netbsd.org/pub/pkgsrc/packages/reports/HEAD/NetBSD-10.0-x86_64/20231225.0728/gobang-0.1.0alpha5nb5/build.log) is outdated dependencies, in particular `num-bigint`. I had a quick look and this seems to have been fix in that crate, so bringing dependencies up-to-date should be enough. What do you say?