Add skip functionality to "dbt-deps" hook

[daniel-bartley]

Describe the feature you'd like

dbt-deps is slow and never skips. :(

dbt-deps should optionally skip if:

• packages.yml is same as main
• $DBT_PATH_TO_PACKAGES exists and is not empty

- repo: local
    hooks:
      - id: dbt-deps
        name: dbt deps if needed
        entry: |
          bash -c \
          'DBT_PATH_TO_PACKAGES="$PATH_TO_DBT"/"$DBT_PACKAGES_DIR"
          dbt_packages_installed="$(find "$DBT_PATH_TO_PACKAGES" -maxdepth 2 -type f | wc --lines)"
          packages_yml_changed=$(git diff --name-only --cached | grep --count $"PATH_TO_DBT"/packages.yml)

          if [ "$dbt_packages_installed" -eq 0 ] || [ "$packages_yml_changed" -eq 1 ] || [ ! -d "$DBT_PATH_TO_PACKAGES" ];
              then dbt deps
              else echo skip dbt deps
          fi'
        language: system

Happy to help but do not currently understand why skipping doesn't work for this command.