Adding bottom padding to error view on About editor

[etoledom]

Closes BETS-48

Description

Adding padding under error view on the about editor.

Now both avatar and about error views have the same space at the bottom

I've chosen to add it only under the error view, as the content already looks well laid out

Testing Steps

• Run the demo app on an old iPhone without notch (iPhone SE)
• Go to the Quick Editor demo screen
• Insert an invalid auth token (to force auth error)
• Open the Quick Editor with About Editor scope
  • Check that there's a space between the lower frame of the error and the screen.

[pinarol]

Looks good 👍

[wpmobilebot]

📲 You can test the changes from this Pull Request in Gravatar Prototype Build by scanning the QR code below to install the corresponding build.

	App Name	Gravatar Prototype Build
	Build Number	2366
	Version	PR #760
	Bundle ID	com.automattic.gravatar-sdk-demo-uikit.prototype-build
	Commit	9bf15cd
	Installation URL	3s6qtnpp3nqr0

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