Use pep 503 compatible wheels index for builds

[frenck]

Proposed change

Adjusts our builds to use our new Wheels index, which is PEP 503 compatible.

This should speed up our release builds tremendously (locally tested and really much faster).

This PR does this by adding the index manually in our Dockerfile right now. Not the cleanest solution, but it does allow us to use it with a minimal impact (just this PR, which we can revert if things are not working as expected).

Once we've learned this is all working as aspected, we will go back to the base images and add these values in the default pip configuration (so that all these flags across our project can be removed).

Once this PR is merged, I'll kick off a nightly build to verify before cutting this into the current beta stream.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Deprecation (breaking change to happen in the future)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests
• 🚀

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• I have followed the perfect PR recommendations
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
• For the updated dependencies - a link to the changelog, or at minimum a diff between library versions is added to the PR description.
• Untested files have been added to .coveragerc.

To help with the load of incoming pull requests:

• I have reviewed two other open pull requests in this repository.

[ludeeus]

🚀