Fix bug with metric_min_improvement_discharge

What's Changed

Bugs

Min improvement discharge was being rounded to an integer, this caused a value of 0.1 to be read as 0 and hence lots of silly exports.

• Bug with metric_min_improvement_discharge being changed to integer by @springfall2008 in #1733

Documentation

• Rename solar_assistant.yaml to solar_assistant_growatt.yaml by @springfall2008 in #1735
• Update bug_report.md by @springfall2008 in #1734

Full Changelog: v8.8.6...v8.8.7