Fix key props; update tests

[katspaugh]

The Table and FixedIcon components had a wrong key prop.
I've also updated the snapshots by running yarn test -u.

How to test

• Open the Table story on localhost
• It shouldn't log a warning about the "key" prop

[github-actions]

ESLint Summary View Full Report

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Type	Occurrences	Fixable
Errors	0	0
Warnings	0	0
Ignored	0	N/A

• Result: ✅ success
• Annotations: 0 total

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^{Report generated by eslint-plus-action}

[ghost]

Travis automatic deployment:
https://pr117--safereactcomponents.review.gnosisdev.com

[katspaugh]

No QA needed, it's just a tiny fix for the React warnings.