Explicitly add npm & yarn step for all-contributors

[ericclemmons]

What Changed

Prefer npm or yarn over npx install-peerdeps.

Why

After prompting to use yarn or not (y/n), install-peerdeps only exited. node_modules nor package.json changed.

Since the purpose is to install both packages together, I listed them explicitly.

It's a great tool & idea (especially if there's concern in all-contributors-cli becoming incompatible with the plugin), but I couldn't continue the setup in https://github.com/ericclemmons/codelift/pull/78 otherwise.

[codecov]

Codecov Report

Merging #895 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #895   +/-   ##
=======================================
  Coverage   84.51%   84.51%           
=======================================
  Files          39       39           
  Lines        2467     2467           
  Branches      316      316           
=======================================
  Hits         2085     2085           
  Misses        300      300           
  Partials       82       82

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[adierkens]

🚀 PR was released in v9.3.3 🚀