feat: add beer name sensor to Keg device integration

[stuartp44]

This pull request updates the MiniBrew integration by adding a new sensor for the keg's beer name, improves dynamic device tracking, and bumps the pymbrewclient dependency version. The main changes are grouped below:

New Sensor Feature:

• Added a KegBeerNameSensor to track and expose the name of the currently loaded beer in each keg. This includes updating the sensor registration logic and documentation. [1] [2]

Device Tracking Improvements:

• Enhanced the logic in add_new_sensors() to track which devices are currently present in the API response, allowing for more robust handling of devices that go offline and come back online. Devices no longer present are removed from the tracked set, supporting re-registration. [1] [2]

Dependency Update:

• Updated the pymbrewclient requirement to version >=1.8.1 to ensure compatibility with the new features.

[github-actions]

Preview Release Created

A preview release has been created for testing this PR.

Version: 0.7.3-preview.19.4bbc58a
Release: https://github.com/stuartp44/hambrewclient/releases/tag/v0.7.3-preview.19.4bbc58a

How to Test

1. Go to the draft release
2. Download minibrew-0.7.3-preview.19.4bbc58a.zip
3. Extract to your Home Assistant custom_components directory
4. Restart Home Assistant
5. Test the changes and report back here

Or install directly via HACS:

# Add custom repository in HACS:
https://github.com/stuartp44/hambrewclient

# Then select version: 0.7.3-preview.19.4bbc58a

---

WARNING: This is a preview release - do not use in production!

Once testing is complete and approved, this PR can be merged for an official release.

[github-actions]

Preview Release Created

A preview release has been created for testing this PR.

Version: 0.7.3-preview.19.1465f24
Release: https://github.com/stuartp44/hambrewclient/releases/tag/v0.7.3-preview.19.1465f24

How to Test

1. Go to the draft release
2. Download minibrew-0.7.3-preview.19.1465f24.zip
3. Extract to your Home Assistant custom_components directory
4. Restart Home Assistant
5. Test the changes and report back here

Or install directly via HACS:

# Add custom repository in HACS:
https://github.com/stuartp44/hambrewclient

# Then select version: 0.7.3-preview.19.1465f24

---

WARNING: This is a preview release - do not use in production!

Once testing is complete and approved, this PR can be merged for an official release.

[github-actions]

🧹 Cleaned up 2 preview release(s) for this PR.