chore: back to reqwest 0.11

As the oauth2 crate still relies in reqwest 0.11, upgrading
to reqwest 0.12 would not bring a real benefit, but add quite
a lot duplicate dependencies.

Cargo.toml

@@ -20,7 +20,7 @@ js-sys = "0.3"
 log = "0.4"
 num-traits = "0.2"
 oauth2 = "4"
-reqwest = "0.12"
+reqwest = "0.11"
 serde = { version = "1", features = ["derive"] }
 time = { version = "0.3", features = ["wasm-bindgen"] }
 tokio = { version = "1", features = ["sync"] }