fix: apply rpi prefix to package name

I suspect our existing package is somehow associated with the
`RaspberryPiFoundation/scratch-gui` git repo and is therefore preventing us from
publishing new versions of the package from this repo.

Therefore I am renaming the package name to
`@RaspberryPiFoundation/rpi-scratch-gui`.

Co-authored-by: Chris Lowis <[email protected]>

Author: sebjacobs

package-lock.json

@@ -1,5 +1,5 @@
 {
-  "name": "@RaspberryPiFoundation/scratch-gui",
+  "name": "@RaspberryPiFoundation/rpi-scratch-gui",
   "version": "11.2.0-svg-sanitization.3",
   "description": "Graphical User Interface for creating and running Scratch 3.0 projects",
   "author": "Massachusetts Institute of Technology",