canarytokens: Existing .xlsx files can now be tokened

[thinkst-louis]

Add MS Excel documents to the list of files which can be uploaded for tokening.

Proposed changes

Just a very short api paramaters update.

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• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update

Checklist

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• Lint and unit tests pass locally with my changes (if applicable)
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• I have added tests that prove my fix is effective or that my feature works
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• Linked to the relevant github issue or github discussion

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