Use dbus-fast unpack_variants option

[mdegat01]

Proposed change

Signature removal from responses has been incorporated into dbus-fast with Bluetooth-Devices/dbus-fast#20 so we now use the unpack_variants option the library includes.

Additionally after Bluetooth-Devices/dbus-fast#22 dbus-fast supports varargs callbacks on signals so when we want to use an annotated method as a callback we no longer need to wrap it in a lambda. This part required a small enhancement to handle kwargs (Bluetooth-Devices/dbus-fast#26) hence the bump to 1.7.0

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (which adds functionality to the supervisor)
• 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:
• Link to cli 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 supervisor tests)
• Tests have been added to verify that the new code works.

If API endpoints of add-on configuration are added/changed:

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