Fix bug in module member checking

Previously wasn’t allowing `const`, `let`, or `var` for any member (even properties).

src/main/java/io/outfoxx/typescriptpoet/ModuleSpec.kt

@@ -100,10 +100,7 @@ private constructor(
          Modifier.READONLY,
          Modifier.GET,
          Modifier.SET,
-         Modifier.STATIC,
-         Modifier.CONST,
-         Modifier.LET,
-         Modifier.VAR
+         Modifier.STATIC
       )
     }