update rust-toolchain to 1.90 (#61)

just updates the toolchain to the current nushell rust-toolchain

Author: AucaCoyan

rust-toolchain.toml

@@ -4,4 +4,4 @@
 # https://rust-lang.github.io/rustup/concepts/profiles.html
 profile = "default"
 # When updating, it might be necessary to run `nix flake update`.
-channel = "1.81.0"
+channel = "1.90.0"

src/typechecker.rs

@@ -1377,7 +1377,7 @@ impl<'a> Typechecker<'a> {
 
     /// Eliminate all type variables that are greater than or equal to `max_var`
     /// * `use_lower`: If true, replace type variables with their lower bound.
-    ///     Otherwise, replace with their upper bound
+    ///   Otherwise, replace with their upper bound
     fn eliminate_type_vars(
         &mut self,
         ty_id: TypeId,