feat: diff-threshold #181
Description
give new option which will show error if coverage difference from base branch is below threshold.
diff-threshold property will set allowed threshold for coverage difference (in percentage) from base branch. for example, if this property is set to to 5 (meaning 5%), error will be shown if current PR doesn't have at least 5% more code covered. similar, if value is set to -5, PR will be allowed to have up to 5% less covered code then base branch.
this property will stack with other rules.