fix: embed attestation can lookup chalk keys in multiple paths

[miki725]

• Followed the steps in the contributor's guide: https://crashoverride.com/docs/other/contributing#filing-the-pull-request
• PR title uses semantic commit messages
• Filled out the template to a useful degree
• Updated CHANGELOG.md if necessary

Issue

chalk was not picking up existing key in CI

for example https://github.com/zaproxy/zaproxy/actions/runs/11739273654/job/32703450631

Description

Previously embed provider only looked up keys in a single location which by default was current working directly.
This is not desirable in CI as placing additional files in PWD can have other side-effects.
As such setup-chalk-action was placing the generated key relative to chalk binary however chalk was not able to lookup that key.

Testing

Try loading existing key in CI