Add PV3 / DC3 sensors to Kostal Plenticore

[SaSa1983]

Proposed change

The current implementation of the Kostal Plenticore integration is missing the PV3/DC3 sensors.
This PR adds them as requested by @stegm in the Feature Reqeust

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)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Additional information

• This PR is related to issue: Kostal inverter is missing 3rd input #50230
• Link to documentation pull request: home-assistant.io/pull/17833

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
• 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

The integration reached or maintains the following Integration Quality Scale:

• No score or internal
• 🥈 Silver
• 🥇 Gold
• 🏆 Platinum

To help with the load of incoming pull requests:

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

[homeassistant]

Hi @SaSa1983,

It seems you haven't yet signed a CLA. Please do so here.

Once you do that we will be able to review and accept this pull request.

Thanks!

[probot-home-assistant]

Hey there @stegm, mind taking a look at this pull request as its been labeled with an integration (kostal_plenticore) you are listed as a codeowner for? Thanks!
_{^{(message by CodeOwnersMention)}}

[stegm]

Hey there @stegm, mind taking a look at this pull request as its been labeled with an integration (kostal_plenticore) you are listed as a codeowner for? Thanks!

Thanks for preparing the PR. I'll will take a look at it soon.

[stegm]

I tested it and it still works as expected for my two solar string setup. The changes seems to be ok for me but some checks are failing (black and flake8).

[frenck]

Ran black --fast homeassistant to resolve the CI issue and pushed it into this branch.