Add pre-commit support

[rdturnermtl]

It would be nice if scspell supported the pre-commit tool as has been done with codespell.

We just need to add a .pre-commit-hooks.yaml file at the top level. It would look something like:

-   id: scspell
    name: scspell
    description: 'spell checking'
    entry: scspell
    args: [--report-only]
    language: python
    types: [text]

The user would then need to add their source controlled dictionaries. The user .pre-commit-config.yaml would use a:

- repo: https://github.com/myint/scspell
  rev: [new version #]
  hooks:
    - id: scspell
      args: [--use-builtin-base-dict,--override-dictionary=/path/to/dictionary_file.txt]

Hopefully this configuration would make things "stateless" enough that it could be run across different machines without any issue.