Update pre commit to remove issue number check

[michaeljcollinsuk]

📝 Summary

Resolves ministryofjustice/analytical-platform#1832

Remove pre-commit restriction for issue number to be included in the commit message.
This is because we have moved from using Jira to Github to track tickets. Additionally, as we are creating issues within the same data-platform repo rather than the project repo, linking to the issue is not straightforward (this is explained in detail here: https://docs.github.com/en/get-started/writing-on-github/working-with-advanced-formatting/autolinked-references-and-urls#issues-and-pull-requests) as it would require the full org-name/repo-name to be prefixed each commit to link to the issue.
Therefore it would be better to link to the issue in the pull request description only.

Alternatively, we could still require some prefix e.g. DPAT-.... However this would not create any link between the issue and commit, and would be purely as our own reference (see previous commit for implementation, can revert to this if preferred).

🔍 What should the reviewer concentrate on?

• Changes to documentation and pre-commit config

🧑‍💻 How should the reviewer test these changes?

• Make a commit, should not require any prefix

📚 Documentation status

• No changes to the documentation are required
• This PR includes all relevant documentation
• Documentation will be added in the future because ... (see #-...)

[ymao2]

LGTM :)