fix: correct password handling syntax in Supabase template SQL scripts

- Updated the password setting syntax to use backticks for command substitution.
- Ensured the echo command for the POSTGRES_PASSWORD variable is correctly formatted for production environments.

blueprints/supabase/template.yml

@@ -325,7 +325,7 @@ config:
     - filePath: /volumes/db/roles.sql
       content: |
         -- NOTE: change to your own passwords for production environments
-        \set pgpass '$(echo "$POSTGRES_PASSWORD")'
+        \\set pgpass \`echo "$POSTGRES_PASSWORD"\`
 
         ALTER USER authenticator WITH PASSWORD :'pgpass';
         ALTER USER pgbouncer WITH PASSWORD :'pgpass';