Tags without own commits gettings wrong dates

[TimoStahl]

Hey @cookpete,
thanks for this nice package.

Actual behaviour

Tags without own commits getting wrong dates.

Expected behaviour

Tags without commits should display the correct dates.

Steps to reproduce

1. commit things
2. tag v1.0.9-rc
3. tag v1.0.9 without new commits

Screenshots

Configuration

auto-changelog@2.0.0

[cookpete]

This should be fixed in 2.1.0. Previously it was using the date of the first commit in that release. For releases without commits (like in your example) it was falling back to the current date. It now grabs the date of each tag instead.