Option to squash commits when analyzing the commit messages

[noahnu]

Is your feature request related to a problem? Please describe.

In one of our monorepos we require squash & merge. We also run monodeploy in dry run to generate a preview. Since we squash and merge, the preview doesn't match what happens when you merge, since we combine the changelog entries.

Describe the solution you'd like

An option that squashes all the commit messages during the parsing stages (i.e. not a real git squash).