fix: update spacing in MethodCard component

[bolariin]

What problem is this PR solving?

I noticed an inconsistency with the spacing between the discount type title and the discount class label for the MethodCard component in the native shopify discount

I noticed a difference with spacing between the discount type title and discount class label for the MethodCard component in the native shopify discount MethodCard component and MethodCard component from this package. This pr resolves the inconsistency by updating the spacing to match the native shopify discount MethodCard.

native shopify discount MethodCard

discount app components MethodCard

discount app components MethodCard after change

Reviewers’ hat-rack :tophat:

• yarn storybook
• review story for MethodCard

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• [x] This PR is safe to rollback.
• [x] I tophatted this change on Storybook.

[bolariin]

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