update tokio to have necessary features for readme example

Author: Shuflduf

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "gemini-rs"
-version = "1.2.0"
+version = "1.2.1"
 edition = "2024"
 license = "MIT"
 authors = [
@@ -20,7 +20,7 @@ secrecy = "0.10"
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1.0"
 thiserror = "2.0"
-tokio = "1.43"
+tokio = { version = "1.43", features = ["full"] }
 
 [dev-dependencies]
 tokio = { version = "1.43", default-features = false, features = [