chore: sync pyproject version to the published 7.8.1 (#1650)

The 7.8.1 add-on hotfix publish (dbc0d1e, [skip ci]) bumped
homeassistant-addon/config.yaml and created the v7.8.1 tag, but left
pyproject.toml at 7.8.0. test_addon_structure.py::test_config_yaml_valid
asserts the add-on version equals the package version, so it fails on
every PR cut from master. Bump pyproject to 7.8.1 to match the released
add-on and the v7.8.1 tag.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: Patch76

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "ha-mcp"
-version = "7.8.0"
+version = "7.8.1"
 description = "Home Assistant MCP Server - Complete control of Home Assistant through MCP"
 readme = "README.md"
 requires-python = ">=3.13,<3.14"