Revert the state class removal in dsmr_reader after bugfix

[Glodenox]

Proposed change

Revert the state class removal done in #75864, as the bug has been fixed at DSMR Reader (dsmrreader/dsmr-reader#1714). I've let the application run for a couple of days and had no more warning messages after their bugfix.

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: DSMR reader sensor has state class total_increasing, but its state is not strictly increasing #55752
• 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
• 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 -> N/A

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.

[home-assistant]

Hey there @depl0y, mind taking a look at this pull request as it has been labeled with an integration (dsmr_reader) you are listed as a code owner for? Thanks!

Code owner commands

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• @home-assistant close Closes the issue.
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[frenck]

Thanks, @Glodenox 👍

Happy Holidays 🎄

../Frenck