chore: Lowercase email on user creation (#175)

There's a few ways to solve this one, but this feels like a good balance
of visibility and pragmaticm.

For reference - we handle this with a DB trigger for `lowcal_sessions`

I've updated any email records on production to be all lowercase.

src/requests/user.ts

@@ -78,7 +78,7 @@ export async function createUser(
     {
       first_name: args.firstName,
       last_name: args.lastName,
-      email: args.email,
+      email: args.email.toLowerCase(),
       is_platform_admin: args.isPlatformAdmin,
     },
   );