warning: use of `format!` to build up a string from an iterator
   --> providers/cloudwatch/src/client/canonical_request.rs:132:31
    |
132 |           let headers: String = self
    |  _______________________________^
133 | |             .headers
134 | |             .iter()
135 | |             .map(|(k, v)| format!("{k}:{v}\n"))
136 | |             .collect::<String>()
    | |________________________________^
    |
help: call `fold` instead
   --> providers/cloudwatch/src/client/canonical_request.rs:135:14
    |
135 |             .map(|(k, v)| format!("{k}:{v}\n"))
    |              ^^^
help: ... and use the `write!` macro here
   --> providers/cloudwatch/src/client/canonical_request.rs:135:27
    |
135 |             .map(|(k, v)| format!("{k}:{v}\n"))
    |                           ^^^^^^^^^^^^^^^^^^^^
    = note: this can be written more efficiently by appending to a `String` directly
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#format_collect
    = note: `#[warn(clippy::format_collect)]` on by default