Updated all ODC Slack links to the new ODC Discord link

[benji-glitsos-ga]

Proposed changes

The ODC Slack is being deprecated in favour of the ODC Discord, so we are updating all our links across all platforms.

Closes issues (optional)

• Update Slack links to Discord #1257

Checklist

(Replace [ ] with [x] to check off)

• Notebook created using the DEA-notebooks template
• Remove any unused Python packages from Load packages
• Remove any unused/empty code cells
• Remove any guidance cells (e.g. General advice)
• Ensure 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).
• Include relevant tags in the final notebook cell (refer to the DEA Tags Index, and re-use tags if possible)
• Clear all outputs, run notebook from start to finish, and save the notebook in the state where all cells have been sequentially evaluated
• Test notebook on both the NCI and DEA Sandbox (flag if not working as part of PR and ask for help to solve if needed)
• If applicable, update the Notebook currently compatible with the NCI|DEA Sandbox environment only 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:

[review-notebook-app]

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[benji-glitsos-ga]

@robbibt Ready for review

[robbibt]

Thanks @benji-glitsos-ga! looks great, I added a discord badge to the readme too. Will let tests pass then accept/merge

[robbibt]

Epic, thanks @benji-glitsos-ga