Update Dockerfile to install prisma globally

Prisma is a dev dependency in the main project. However, it is
needed in the image so we can run the migrations before starting
the server up. This installs it globally in the image since it
won't be installed using the project's `package.json`.

Signed-off-by: Alex Sears <me@alexsears.com>

scripts/start.sh

@@ -2,5 +2,5 @@
 set -x
 
 /calcom/scripts/wait-for-it.sh ${DATABASE_HOST} -- echo "database is up"
-# npx prisma migrate deploy --schema /calcom/packages/prisma/schema.prisma
+npx prisma migrate deploy --schema /calcom/packages/prisma/schema.prisma
 yarn start