Remove trailing slash from path
Remove trailing slash from path

A change of `commitIdFromGitRepo` in nixpkgs/lib/sources.nix
resulted in the error message
"attribute '.git' missing at nixpkgs/lib/sources.nix:7:32" when
executing darwin-rebuils switch.
The commit with the change is
https://github.com/NixOS/nixpkgs/commit/c9214c394b248e1f26e45dbe1be2bd82363af3a6

Removing the trailing slash resolves the error.

LnL7/nix-darwin