[Website] change width of the additional case studies cards

[bullet03]

• change width of additional case-studies cards, so 5 cards fit in a row instead of 4

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[AlyaBoiko]

Verified, works as expected. Reviewed and tested by QA

[bullet03]

@pabloem, @aijamalnk, could you, please, help with review of current PR?

[aijamalnk]

LGTM, thank you!