fix: yarn cache path should be a string

[siddharthab]

PR Checklist

Please check if your PR fulfills the following requirements:

• [] Tests for the changes have been added (for bug fixes / features)
• [] Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature (please, look at the "Scope of the project" section in the README.md file)
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the current behavior?

Issue: #1678

What is the new behavior?

Does this PR introduce a breaking change?

• [] Yes
• No

Other information

[gregmagolan]

Thanks for the fix!

[gregmagolan]

Fixes #1678

[siddharthab]

Thank you for the quick merge. Do you have guidance on when this change will be in a release? Or can I use the commit hash directly?

[alexeagle]

We don't publish release snapshots yet, and the layout of the source repo doesn't match what we publish (has a bunch of development dependencies for example) so the easy way to pull this into your project is to patch it, see https://github.com/bazelbuild/rules_nodejs/blob/master/docs/index.md#patching-the-built-in-release

[siddharthab]

Thanks! A patch file should work just fine.