Bump bimmer_connected to 0.7.15 and fix bugs

[rikroe]

Proposed change

Bump bimmer_connected from 0.7.14 to 0.7.15.
Release notes: https://github.com/bimmerconnected/bimmer_connected/releases/tag/0.7.15
Release diff: bimmerconnected/bimmer_connected@0.7.14...0.7.15

The dependency bump of the library fixes #34776 and partly #46378.
Changes to device_tracker.py fixes #46378.
Changes to __init__.py fixes bimmerconnected/bimmer_connected#265.

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

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes BMW Connected Drive gives "KeyError: 'executionStatus'" when locking #34776, fixes bmw_connected_drive/device_tracker - TypeError: 'NoneType' object is not subscriptable #46378, fixes stopped updating bimmerconnected/bimmer_connected#265
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
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• Tests have been added to verify that the new code works.

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

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• 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.
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[probot-home-assistant]

Hey there @gerard33, mind taking a look at this pull request as its been labeled with an integration (bmw_connected_drive) you are listed as a codeowner for? Thanks!
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[MartinHjelmare]

Thanks!