New install-fish-shell action added

[marcransome]

🪄 fish-shop/install-fish-shell is the latest addition to the fish-shop family and provides an easy way to install fish shell in your macos-* and ubuntu-* based GitHub-hosted runner workflows:

jobs:
  install-fish-shell:
    runs-on: ubuntu-latest
    steps:
      - name: Install fish shell
        uses: fish-shop/install-fish-shell@v1

Don't mind the fish! 🐟