fix: restore ability to use web-identity-token-file (issue: #124)

[stephenc]

Issue #124

Description of changes:

The validation logic for credentials was failing for the web-identity-token-file use case which needs to be handled similarly to the OIDC case as I understand it

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[peterwoodworth]

This looks good to me, and makes sense. I need to set this up so I can actually properly test this before approving, will get to that next week.

[stephenc]

I'm just driving by. Feel free to do what you want with this. It's not blocking me as we have OIDC set up and working... I was just trying to understand what goes on underneath the covers 🤣

[peterwoodworth]

Yeah I think you're right, I still just need to test it. This week was busier than expected for me, but I should be able to try next week

[Udbv]

I spend several hours to understand why web-identity-token-file throw error and none created an issue :-)

[stephenc]

@Udbv feel free to try uses: stephenc/configure-aws-credentials@1b2bf9cf72eda1d55257a2d29cb418fb30410136 as I suspect that will solve your issue ;-)

[peterwoodworth]

@stephenc I didn't have the capacity approve this while we were getting internal approvals for v3, but thank you for the contribution to help me kick off this fix in v3. I really appreciate it