Add .vscode to .prettierignore (keystonejs#7211)

* Add .vscode to .prettierignore
To prevent `yarn lint` errors on `.vscode/launch.json` file, which is in "JSON with Comments" format.

We already have `.vscode` in `.gitignore`, so excliding it from prettier
is a good step too.

* Convert to mask

* No changeset required

Co-authored-by: Daniel Cousens <413395+dcousens@users.noreply.github.com>

.prettierignore

@@ -11,3 +11,4 @@ docs/public/assets/
 prisma-utils/src/generated
 nexus-typegen.ts
 tests/test-projects/live-reloading/schemas/syntax-error.js
+*.vscode