Allow requirement file in hatch environment depenedencies

[ketozhang]

Description

Add feature to allow use of requirements file when specifying hatch environments.

[tool.hatch.envs.<env>.dependencies]
dependency-file = "requirements.txt"

Other Additional Information:

My use case is docs environment where I have to keep a separate requirements/docs.txt file for local build and CI build of docs.
The CI is from RTD which only allows requirement files. I have other options which I'd like to not explore right now.

[ketozhang]

@ofek Is there any way to do this in hatch right now (e.g., via plugin)?

[ofek]

• https://hatch.pypa.io/latest/plugins/environment-collector/reference/
• https://github.com/DataDog/integrations-core/blob/10bd0a9c9198438483df99dbe4b3c3547621fd19/datadog_checks_dev/datadog_checks/dev/plugin/hatch/environment_collector.py#L69-L154

[dyve]

Having hatch or a hatch plugin connect with requirements for environments (docs, dev) would be great. Also for integration with GitHub Dependabot.