Fix method names in NamedType class to use correct TypeScript override syntax for toURN and toString methods.

src/di/NamedType.ts

@@ -16,11 +16,11 @@ export class NamedType extends Type {
     return super.equals(other) && other instanceof NamedType && this.getName() === other.getName();
   }
 
-  public overridetoURN(): string {
+  public override toURN(): string {
     return `urn:namedtype:${super.getType()}#${this._name}`;
   }
 
-  public overridetoString(): string {
+  public override toString(): string {
     return `${super.getType()}#${this._name}`;
   }
 }