fix(payload_api, git_diff): Accessing correct property in payload and Replacing --quiet with --no-patch in git diff

[codesculpture]

1. Replacing github.context.payload.head with github.context.payload.pull_request?.head

github.context.payload.head is always undefined and github doc also there is no evidence this exist,
So while trying github.context.payload.pull_request?.head this returns the expected head object and can propogates to fork
and also fork is boolean not a string.
this is found during why the action reached this if block due to avoid git merge-base and seems it could be a accidental mistake

2. Replacing --quiet with --no-patch

As of now, seems every git commands are returning exitcode and if the exit code is none other than 0
we are assuming that operation is not completed successfully which is correct but except
git diff --quiet would return exit code 0 if there are no differences, but returns 1 if there is any differences.
as they mentioned here , --quiet would add
--exit-code.

Make the program exit with codes similar to diff(1). That is, it exits with 1 if there were differences and 0 means no differences.

As they mentioned here.
So seems it not expected, but we have similar flag to run git diff with no outputs, which is --no-patch

These all are found while try to avoid fetching more histories to save time from the eslint-changed-files action and this is a follow up of tj-actions/eslint-changed-files#1633

[tj-actions-bot]

Thanks for implementing a fix, could you ensure that the test covers your changes if applicable.

[codesculpture]

Ran test, some tests failed but all are paths related because i ran in windows, where paths were separated with double slashes \\ which is different from non-windows \ single slash, so is there anything i need to @jackton1 :)

[jackton1]

Hi @codesculpture, it looks good. Thanks

[jackton1]

@all-contributors please add @codesculpture for code and bug

[allcontributors]

@jackton1

I've put up a pull request to add @codesculpture! 🎉