remove dependency on dev yardstick

[simonpcouch]

Following up on #684 in anticipation of a tune patch release after rsample. The functionality added in that PR won't kick in with previous yardstick versions, so this PR temporarily removes the unneeded dev dependency.

If we merge this, we should open an issue reminding us to revert these changes after the upcoming tune release. :)

[simonpcouch]

Cloud revdepcheck ref for this PR is "6272d95f-7fdf-44c8-bbab-c6d27e3b7f40".

[simonpcouch]

One new failure, with stacks:

Status: BROKEN

── Newly failing

✖ checking re-building of vignette outputs ... WARNING

── Before ─────────────────────────────────────────────────────────────────────────────────────
0 errors ✔ | 0 warnings ✔ | 0 notes ✔

── After ──────────────────────────────────────────────────────────────────────────────────────
❯ checking re-building of vignette outputs ... WARNING
  Error(s) in re-building vignettes:
    ...
  --- re-building ‘basics.Rmd’ using rmarkdown
  
  Quitting from lines 293-300 [unnamed-chunk-17] (basics.Rmd)
  Error: processing vignette 'basics.Rmd' failed with diagnostics:
  Can't subset columns that don't exist.
  ✖ Column `latency` doesn't exist.
  --- failed re-building ‘basics.Rmd’
  
  --- re-building ‘classification.Rmd’ using rmarkdown
  --- finished re-building ‘classification.Rmd’
  
  SUMMARY: processing the following file failed:
    ‘basics.Rmd’
  
  Error: Vignette re-building failed.
  Execution halted

0 errors ✔ | 1 warning ✖ | 0 notes ✔

🧐

[topepo]

I just tried and got

revdepcheck::cloud_status()
SUCCEEDED: [0/0/27/0 - 27] 00:18:50 | ETA: Done

I'll merge and we'll see what happens!

[github-actions]

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