aws-c-mqtt: update aws-c-http/0.8.1

[toge]

Specify library name and version: aws-c-mqtt/*

• update aws-c-http/0.8.1

aws-c-mqtt has already released 0.10.1.
But it requires newer aws-c-io version.
To simplify this PR, I stop to update aws-c-mqtt to 0.10.1.

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• I've used a recent Conan client version close to the currently deployed.
• I've tried at least one configuration locally with the conan-center hook activated.

[conan-center-bot]

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