Add skip_release flag to bypass GitHub releases and tagging

[bobbyiliev]

Added a new skip_release flag that allows users to bypass GitHub release and tag creation while still publishing chart artifacts to the pages branch.

Some workflows only need to publish chart artifacts without managing GitHub releases and tags. Especially for monorepos.

Example:

- name: Run chart-releaser
  uses: helm/[email protected]
  with:
    skip_release: true
    packages_with_index: true
  env:
    CR_TOKEN: "${{ secrets.GITHUB_TOKEN }}"