Admin Reskin: Add more spacing below the plugin card header.

Follow-up to [61646].

Props wildworks, mukesh27, shailu25, noruzzaman, darshitrajyaguru97, SergeyBiryukov.
Fixes #64987.

git-svn-id: https://develop.svn.wordpress.org/trunk@62290 602fd350-edb4-49c9-b593-d223f7449a82