Action erroniously passing and showing duplicate lints with `--all-targets` enabled

[yaahc]

I noticed theres a big fat WIP on this repo so I'm not sure you're interested in bug reports on this action yet but incase you are I figured I'd file this one.

I tried testing out the new clippy action in this PR. It worked in so far as it showed the nice clippy warnings with the full output of the warning in the PR and it took minimal work to setup, which is fantastic 👍

The problem is that first of all, it showed as passing when clippy (or maybe just the action running clippy?) exited with a 101 code. Second, when --all-targets was enabled it showed the lints twice. Now I know that the --all-targets thing is reproducible outside of actions-rs so its not actually a bug with your code, so this second bit is probably more of a feature request than a bug report, but it would be nice if it filtered out identical error msgs.

[svartalf]

Hey, @yaahc! Feel free to create bug reports here, any feedback is valuable :)

In a current state this Action is more like an experiment to see if we will be able to create decent clippy annotations without sending them via GitHub API, that's definitely prone to errors. Also it will get rid of the GITHUB_TOKEN requirement, would be really great to do that.
Yet, it is using undocumented GitHub thing (I'm not even sure about the exact status of that feature) to create annotations and the intended replacement is in unknown state since October; so I'm not sure if is worth to replace the actions-rs/clippy-check right now, it could potentially break any time.

As for the bug itself, thank you for reporting it, I'll take a look into it :)