Update Cargo.toml, remove redundant reqwest dev-dependency

[abd0-omar]

avoid duplication as it's already in the main dependencies so no need for it in the dev-dependency

quoting the book at chapter 7.2.2 page 168 [dependencies]

[...]

We need the json feature flag to serialize/deserialize JSON payloads reqwest = { version = "0.11", default-features = false, features = ["json", "rustls-tls"] } [dev-dependencies]

Remove reqwest's entry from this list

[...]

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Description of changes:

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