fix trailing slash in configuration builder

src/config.rs

@@ -141,6 +141,14 @@ macro_rules! make_config {
                 )+)+
                 config.domain_set = _domain_set;
 
+                if config.domain_set {
+                    if config.domain.ends_with('/') {
+                        println!("[WARNING] The configured domain ends with a trailing slash.");
+                        println!("[WARNING] The trailing slash is getting removed.");
+                        config.domain = config.domain.trim_end_matches('/').to_string();
+                    }
+                }
+
                 config.signups_domains_whitelist = config.signups_domains_whitelist.trim().to_lowercase();
                 config.org_creation_users = config.org_creation_users.trim().to_lowercase();