Provide better errors on unknown type in cyclic definitions.

Let's consider the following case:

  ```
  type Var =
    Integer

  type Vars =
    List<Var>
  ```

  This incorrectly reports an infinite cycle; due to the inability to
  properly type-check `Var` which is also a dependent var of `Vars`. Yet
  the real issue here being that `Integer` is an unknown type.

  This commit also upgrades miette to 7.2.0, so that we can also display
  a better error output when the problem is actually a cycle.

crates/aiken/Cargo.toml

@@ -34,7 +34,7 @@ hex = "0.4.3"
 ignore = "0.4.20"
 indoc = "2.0"
 inquire = "0.6.2"
-miette = { version = "5.5.0", features = ["fancy"] }
+miette.workspace = true
 num-bigint = "0.4.3"
 ordinal = "0.3.2"
 owo-colors = { version = "3.5.0", features = ["supports-colors"] }