feat: enable user signup in configuration

config.yml

@@ -29,7 +29,7 @@ db:
 security:
     insecure_cookies: false # should be set to 'false', except when not running with HTTPS (e.g. on localhost)
     cookie_max_age: 172800
-    allow_signup: false
+    allow_signup: true
     signup_captcha: false
     invite_codes: true # whether to enable invite codes for overriding disabled signups
     disable_frontpage: false