ssh-agent does not work with backslashed path seperator on windows machine

[shelper]

I have an action script that uses ssh-agent, and it works fine on ubuntu for access private repo using deploy key, but failed on windows,
the error message is

Load key "C:\\Users\\runneradmin/.ssh/key-52016bfd3f72432689e062517edb001705ef0a8d1af12eb63b188417c75ca43e": invalid format

and i believe the reason is that windows just cannot load key with / as its path seperator, we need to change / to \\ to make it work on windows. e.g. the key file path should be:
C:\Users\runneradmin\.ssh\key-52016bfd3f72432689e062517edb001705ef0a8d1af12eb63b188417c75ca43e

[cardoe]

I've written a compatible action that has some extra tests and cleanups along with GitHub Enterprise support. The paths might work better since it uses path.join everywhere. https://github.com/marketplace/actions/ssh-agent-deploy-key give it a whirl if that helps.