fix: close up and quote password

homeserver.yaml.tmpl

@@ -2118,7 +2118,7 @@ email:
   # authentication is attempted.
   #
   smtp_user: {{ env "SMTP_USER" }}
-  smtp_pass: {{ secret "smtp_password" }}
+  smtp_pass: "{{ secret "smtp_password" }}"
 
   # Uncomment the following to require TLS transport security for SMTP.
   # By default, Synapse will connect over plain text, and will then switch to
@@ -2247,6 +2247,7 @@ email:
     # Subject to use when sending a verification email to assert an address's
     # ownership.
     #email_validation: "[%(server_name)s] Validate your email"
+  {{ end }}