fix: allow resetting to recommended nonce of 0

[iamacook]

What it solves

Resolves #1311

How this PR fixes it

The typeof recommendedNonce is checked that it is a 'number' instead of whether it is truthy.

How to test it

1. Create a new Safe and create a new transaction.
2. Edit the nonce to >0 and reset the nonce to the recommended value.
3. Observe that it sets to 0.

Screenshots

[github-actions]

Branch preview

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https://recommended-nonce--webcore.review-web-core.5afe.dev

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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}

[katspaugh]

Verified, it resets to zero. ✅