1.3 was a breaking release

[Vampire]

Upgrading the node version is a breaking change.
So actually 1.3 should have been 2.0.
I also did this wrong in the past and learned this from my action's users.
If the action is used on a custom self-hosted runner, there is no guarantee that the new Node version is available and so updating the node version is a breaking change.

Feel free to decide how you proceed or whether you ignore the breaking change.
Back then I reverted the change, cut a new release and did the change in a directly following major version release.

[DamianReeves]

Apologies for staleness... I need to check my notifications in GitHub a bit more. Will be refreshing between now and end of year