Allow `args` in `install` input

[pcaversaccio]

My usual CI workflow is the following:

- name: Install pnpm
  uses: pnpm/action-setup@0977fd99725f1db4007ccb2928dbb4e90d06cc86 # v6.0.10
  with:
    cache: true
    run_install: |
      - args: [--prefer-offline, --frozen-lockfile]

while --frozen-lockfile is enabled by default in the CI (see here) there is no way I can configure --prefer-offline in the current setup without running the installation in a separate step again. Before switching to this new action, it's a hard requirement for me to have the ability to configure the install options.