3.1.2 breaking changes

[USA-RedDragon]

I noticed that 3.1.2 broke my CI workflows because the action inputs removed working-directory. After having a look, I found undocumented breaking changes in the codebase buried in merge commits. Note the release notes: https://github.com/codecov/codecov-action/releases/tag/v3.1.2

1. 40a12dc#diff-1243c5424efaaa19bd8e813c5e6f6da46316e63761421b3e5f5c8ced9a36e6b6L86-L88 - This commit removes several options, none of which are updated in the README, and the commit message would lead people to believe the commit was intended as just a version bump.
2. Another opportunity arose with commit 030a000 that could have been an indicator that breaking changes occurred and that a semver major version or at least a note in the release notes that the inputs had changed.

If this project isn't following semver, that's alright, but having to dig into the code as a user in order to figure out why my workflows broke isn't a good UX. Please call these out in the future.

What's the alternative to working-directory? Is that functionality removed? Is #110 no longer valid?

[thomasrockhu-codecov]

@USA-RedDragon this is absolutely my fault, I'll make a PR this week and release a new version