chore(showcase): Adds www.projectival.de (#12596)
chore(showcase): Adds www.projectival.de (#12596)

* Adds www.projectival.de

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## Description
Adds https://www.projectival.de/

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* Update sites.yml

* chore: format

gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby,ChristopherBiscardi/gatsby,ChristopherBiscardi/gatsby,gatsbyjs/gatsby