Fully define dependencies for async support via optional dependency group

[wevonosky]

The current docs suggest adding aiohttp as a dependency to create an async app, but this creates a direct dependency on aiohttp for consumers of slack-bolt on what is is really a transitive dependency for the consumer of slack-bolt. This is especially important because this leaves it to consumers to find compatible versions of slack-bolt and aiohttp without the aide of a package manager.

slack-bolt should define an optional dependency group and include aiohttp so that consumers of this library don't need to maintain a dependency on a transitive. Consumers would be able to uv add slack-bolt[async] for example to include the optional dependencies.

Category (place an x in each of the [ ])

• slack_bolt.App and/or its core components
• slack_bolt.async_app.AsyncApp and/or its core components
• Adapters in slack_bolt.adapter
• [] Others

Requirements

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[WilliamBergamin]

Hi @wevonosky thanks for opening this issue 💯

This is similar to #1423, this issue brings up some valid arguments to implementing something like pip install slack-bolt[async]. This would be a valid addition to the project!

We will need to figure out how to properly support the optional dependency since this project supports Python >=3.7 and aiohttp currently supports Python >=3.9. A solution could be to only support slack-bolt[async] for Python >=3.9 🤔

In the meantime if anyone encounters this issue feel free to react with 👍 to express your interest in it