Action reporting wrong SHA in a Pull Request

[rhuanbarreto]

In the following line:

run-report-action/helpers.ts

Line 11 in 7887579

const { repo, serverUrl, sha } = github.context;

the sha ref the action is printing in a Pull Request is not the right reference to use.

The right one is context.payload.pull_request.head.sha.

An example for another github action:

https://github.com/chromaui/chromatic-cli/blob/b75294bf6dd44ce99846daed9164ba2ba343a0a3/action-src/main.ts#L19-L84