Add pre-commit hook to avoid duplicates

[emmaai]

Proposed changes

Add pre-commit hook to check duplicate notebooks before commit, both locally and remotely. Aiming to save human from sanity-checking as much as possible.

Closes issues (optional)

N/A
If there are duplicates, the output should be

ubuntu@ip-10-0-13-183:~/work/dea-notebooks$ git commit -a -m "add test"
Check for duplicate .ipynb filenames.....................................Failed
- hook id: check-duplicate-ipynb
- exit code: 1

Checking for duplicate .ipynb filenames...
Duplicate .ipynb filenames detected in repository and staged changes:
test1.ipynb
Commit rejected! Ensure unique .ipynb filenames.

Checklist

If this is a notebook, then have you:

• Checked the structure of the notebook follows our DEA-notebooks template
• Removed any unused Python packages from Load packages
• Removed any unused/empty code cells
• Removed any guidance cells (e.g. General advice)
• Ensured that all code cells follow the PEP8 standard for code. The jupyterlab_code_formatter tool can be used to format code cells to a consistent style: select each code cell, then click Edit and then one of the Apply X Formatter options (YAPF or Black are recommended).
• Included relevant tags in the final notebook cell (refer to the DEA Tags Index, and re-use tags if possible)
• Tested notebook on the DEA Sandbox
• Cleared all outputs, run notebook from start to finish, and save the notebook in the state where all cells have been sequentially evaluated
• If applicable, update the Notebook currently compatible with line below the notebook title to reflect the environments the notebook is compatible with
• Check for any spelling mistakes using the DEA Sandbox's built-in spellchecker (double click on markdown cells then right-click on pink highlighted words). For example: