style: cargo fmt -- tower.rs test assertions

The two multiline assert!(validate_standard_headers(...)) calls fit
within max_width=100, so nightly cargo fmt collapses them to single
lines. Fixes the Code Formatting check on CI.

Author: SIDDARTHAREDDY8

crates/rmcp/src/transport/streamable_http_server/tower.rs

@@ -742,18 +742,14 @@ mod standard_header_init_tests {
     #[test]
     fn initialize_accepts_missing_mcp_method_header() {
         let headers = headers_with(None);
-        assert!(
-            validate_standard_headers(&headers, &initialize_message(), no_tool_schema).is_ok()
-        );
+        assert!(validate_standard_headers(&headers, &initialize_message(), no_tool_schema).is_ok());
     }
 
     /// A supplied Mcp-Method header matching the initialize body is accepted.
     #[test]
     fn initialize_accepts_matching_mcp_method_header() {
         let headers = headers_with(Some("initialize"));
-        assert!(
-            validate_standard_headers(&headers, &initialize_message(), no_tool_schema).is_ok()
-        );
+        assert!(validate_standard_headers(&headers, &initialize_message(), no_tool_schema).is_ok());
     }
 }