[mlir][OpInterfacesGen][NFC] Add newline after traits declaration (llvm#85633)

Slightly improve the readability of the tablegen-generated code.

Co-authored-by: Orest Chura <[email protected]>

Author: andrey-golubev

mlir/tools/mlir-tblgen/OpInterfacesGen.cpp

@@ -533,7 +533,7 @@ void InterfaceGenerator::emitInterfaceDecl(const Interface &interface) {
      << "struct " << interfaceTraitsName << " {\n";
   emitConceptDecl(interface);
   emitModelDecl(interface);
-  os << "};";
+  os << "};\n";
 
   // Emit the derived trait for the interface.
   os << "template <typename " << valueTemplate << ">\n";