Update unlock icon for tile card lock features

[krazos]

Proposed change

In PR#116157 (core), the icon for an unlocked lock was recently changed from mdi:lock-open to mdi:lock-open-variant to make it easier to visually distinguish between locked and unlocked states:

I propose to make the same change to the unlock button in the newly-added tile card lock features for the same reason and in the interest of consistency across the UI.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New feature (thank you!)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example configuration

type: tile
entity: lock.front_door
features:
  - type: lock-commands

Additional information

• This PR fixes or closes issue: fixes #
• This PR is related to issue or discussion:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• There is no commented out code in this PR.
• 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