Add dependency caching to pnpm

[MikeMcC399]

• This is an enhancement suggestion in response to issue PNPM Cache does not work properly #1040.

What would you like

When the cypress-io/github-action processes a project with a pnpm-lock.yaml lockfile from the pnmp package manager it should cache dependencies from the pnpm store. The location of the store can be found from the command pnpm store path.

Why is this needed?

The cypress-io/github-action caches dependencies from npm and from Yarn Classic for other project types (see Installation for lockfile names). Not providing this functionality for pnpm projects is inconsistent.

The benefit for users of pnpm projects with larger volumes of dependencies lies in shorter run times for workflows, providing results faster. Additionally all GitHub plans have either limits on the number of action minutes used or a cost associated with action minutes, so reducing run times is also beneficial to keep inside limits or to reduce costs. (See About Billing for GitHub Actions).

Other

• As a workaround PR test: add npm caching to pnpm examples #1043 is proposed which manually adds caching into the workflow since it is not available in the action itself. Edit: This is now available as an example. See the README > pnpm section.