fix(functions): cors-rust example

[dehy]

Summary

Checklist

• I have reviewed this myself.
• I have attached a README to my example. You can use this template as reference.
• I have updated the project README to link my example.

Details

The current Rust CORS example does compile

error[E0433]: failed to resolve: use of undeclared crate or module `response`
 --> function/src/lib.rs:5:32
  |
5 | pub fn with_permissive_cors(r: response::Builder) -> response::Builder {
  |                                ^^^^^^^^ use of undeclared crate or module `response`
  |
help: a type alias with a similar name exists
  |
5 | pub fn with_permissive_cors(r: Response::Builder) -> response::Builder {
  |                                ~~~~~~~~
help: consider importing this module
  |
1 + use http::response;
  |
error[E0433]: failed to resolve: use of undeclared crate or module `response`
 --> function/src/lib.rs:5:54
  |
5 | pub fn with_permissive_cors(r: response::Builder) -> response::Builder {
  |                                                      ^^^^^^^^ use of undeclared crate or module `response`
  |
help: a type alias with a similar name exists
  |
5 | pub fn with_permissive_cors(r: response::Builder) -> Response::Builder {
  |                                                      ~~~~~~~~
help: consider importing this module
  |
1 + use http::response;
  |
For more information about this error, try `rustc --explain E0433`.
error: could not compile `cors-rust` (lib) due to 2 previous errors

This PR explicitly reference the http module in the method parameters.

[thomas-tacquet]

Thanks!! I tested it and it works fine 👌