Fix HomeMatic variables

[danielperna84]

Description:

In the pyhomematic repository it was reported, that the variables feature stopped working in HASS 73. The dependency has been updated (to 0.1.45), which fixes the problem. The issue: https://github.com/danielperna84/pyhomematic/issues/143

Checklist:

• The code change is tested and works locally.
• Local tests pass with tox. Your PR cannot be merged unless tests pass

If the code communicates with devices, web services, or third-party tools:

• New dependencies have been added to the REQUIREMENTS variable (example).
• New dependencies are only imported inside functions that use them (example).
• New or updated dependencies have been added to requirements_all.txt by running script/gen_requirements_all.py.