Include prof gem group in sorbet workflow

[dduugg]

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An attempt to fix #15119

I'm not sure how to kick off a test for this workflow, and I have issues with tapioca locally that I'm still attempting to resolve Bundler::LockfileError: You must use Bundler 2 or greater with this lockfile.)

[carlocab]

Sounds right to me.

[MikeMcQuaid]

Looks good, thanks @dduugg!