catch2 time units are ignored when graphing and generating alerts

[paradust7]

When using the "catch2" extractor, the time units, "ms", "us", etc, are extracted and printed, but otherwise ignored.

This results in broken graphs when the time is near a unit boundary:

It also results in false alerts:

[wwerkk]

Any news on this? getRatio doesn't involve unit calculation atm, though it seems like an easy fix for a problem that makes this action pretty useless for catch:

github-action-benchmark/src/write.ts

Line 567 in 8e74972

function getRatio(tool: ToolType, prev: BenchmarkResult, current: BenchmarkResult) {