Add .pnpm-store to gitignore (#6566)

Adds .pnpm-store to gitignore. It's a cache folder that sometimes
appears in certain scenarios that would never need to be checked into
git.

┆Issue is synchronized with this [Notion
page](https://www.notion.so/PR-6566-Add-pnpm-store-to-gitignore-2a16d73d365081319220f90516cfad3c)
by [Unito](https://www.unito.io)

Author: benceruleanlu

.gitignore

@@ -18,6 +18,7 @@ yarn.lock
 .stylelintcache
 
 node_modules
+.pnpm-store
 dist
 dist-ssr
 *.local