vim-plugins: update source hash for command-t
vim-plugins: update source hash for command-t

And use fetchzip instead of fetchurl towards github.com to not let this
happen again. (fetchzip checks the hash on the *extracted* archive, so
changes in compression algo etc. doesn't change the hash.)

SymbiFlow/nixpkgs,NixOS/nixpkgs,triton/triton,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,triton/triton,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,triton/triton,NixOS/nixpkgs,triton/triton,NixOS/nixpkgs,NixOS/nixpkgs,triton/triton,SymbiFlow/nixpkgs,NixOS/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,triton/triton,NixOS/nixpkgs,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs,NixOS/nixpkgs,triton/triton,SymbiFlow/nixpkgs,NixOS/nixpkgs,triton/triton,SymbiFlow/nixpkgs,SymbiFlow/nixpkgs,NixOS/nixpkgs