Update workflows permission to allow forked PRs to have commented results

[jasonwilliams]

Set the right permissions on workflows so benchmarks and test262 can be commented back to the PR

For a while we haven't been able to have test262 and benchmarks be commented back to forked PRs, it looks like there is a solution to this now.
boa-dev/criterion-compare-action#62 (comment)

So if the above is true, we just need to add the permissions line to here and here