Chore/replace deprecated devcontainer image

[bj00rn]

Upgrade devcontainer base image

Get devcontainer configuration up to date to make it easier to contribute.

BREAKING CHANGE: dev script will not work outside devcontainer.

fixes #365

• Upgrade devcontainer to latest configuration from integration_blueprint https://github.com/ludeeus/integration_blueprint/blob/067cc6987a8c9adfa1e337b49f3a3c6c24641d97/.devcontainer.json
  • python 3.12 required for HA 2024.4 and later
  • remove deprecated tasks for HA version selection
• Add workaround for nordpool dependency not resolving due to name collision with integration package
  • Use mount to resolve custom_components instead of relying on PYTHONPATH https://github.com/ludeeus/integration_blueprint/issues/130
• Add requirements.txt for development and pin HA to 2024.6.4 for now as per integration_blueprint