feat: Add cargo-edit

Used for the "cargo upgrade" command, which also updates the Cargo.toml.

Should eventually be upstreamed to cargo. Currently cargo-edit has some
issues with the index it uses, resulting in long loading times.

See: https://internals.rust-lang.org/t/feedback-on-cargo-upgrade-to-prepare-it-for-merging/17101

home/neovim.nix

@@ -73,6 +73,7 @@ in
     cargo-license
     cargo-feature
     cargo-tarpaulin
+    cargo-edit
     rust-analyzer
     bacon
     clippy