fix!: fix failure when api key as param and not env

BREAKING CHANGE:

- Rename `ClientError.ApiKeyError` to `MissingApiKey`.
- Rename `ClientError.ReadResponseTextError` to `ClientError.UnreadableResponseText`.

Cargo.toml

@@ -19,6 +19,8 @@ futures = "0.3.30"
 reqwest = { version = "0.11.24", features = ["json", "blocking", "stream"] }
 serde = { version = "1.0.197", features = ["derive"] }
 serde_json = "1.0.114"
+strum = "0.26.1"
+strum_macros = "0.26.1"
 thiserror = "1.0.57"
 tokio = { version = "1.36.0", features = ["full"] }