Fix: rm Multisig in copy

[katspaugh]

Remove Multisig from a piece of text on the Welcome page.

Also install a missing dev dependency.

[github-actions]

CLA Assistant Lite All Contributors have signed the CLA.

[github-actions]

ESLint Summary View Full Report

Annotations are provided inline on the Files Changed tab. You can also see all annotations that were generated on the annotations page.

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

• Result: ✅ success
• Annotations: 0 total

---

^{Report generated by eslint-plus-action}

[github-actions]

Deployment links

🟠 Safe Rinkeby	⚪ Safe Mainnet	🟣 Safe Polygon	🟡 Safe BSC	⚫ Safe Arbitrum	🟢 Safe xDai

[coveralls]

Pull Request Test Coverage Report for Build 1491280124

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 31.825%

---

Totals
Change from base Build 1490055562:	0.0%
Covered Lines:	2979
Relevant Lines:	8350

---

💛 - Coveralls

[github-actions]

E2E Tests Passed ✅
Check the results here: https://github.com/gnosis/safe-react-e2e-tests/actions/runs/1491320184