Fix benchmark action for pull requests from forks

[siku2]

Description

The workflow currently doesn't work on pull requests because the GITHUB_TOKEN only has read-only permissions.
There seems to be no way to solve this currently so this PR removes the comment functionality entirely.
Instead, the results are now logged to the console which is less exciting but it should at least work.

Fixes #1311

[teymour-aldridge]

Perhaps this could be rewritten as two separate actions – one to run on push (with comments) and one to run on pull requests (without comments).

[siku2]

@teymour-aldridge where would it post the comments on push though? It could add it as a comment to the commit itself but the commit should already be benchmarked before it is added to the master branch, right?

[teymour-aldridge]

Oh, that's true. Perhaps a try/except sort of thing is possible in bash – so that it tries to add a comment, and if it lacks permission it will just log the output?
Disclaimer: my bash scripting is really bad.

[siku2]

@teymour-aldridge I thought about this too, but how often is there going to be a pull request that doesn't originate from a fork?
It would be possible to do it by putting the affected steps behind a condition but I doubt it's worth the effort for such a rare case.

[teymour-aldridge]

That's true. I've noticed that some Github apps are able to add comments for pull requests for third parties, but that would be something to look into for a later PR I think.

[siku2]

I was curious about that too but I think they're all using integrated apps to do it.
I also looked into whether this affects #1307 and luckily it doesn't. Codecov has found an interesting way to solve this without depending on any secrets (see this comment for an explanation).