Fixed an instance of " in generated code

Author: alan412

src/blocks/mrc_steps.ts

@@ -220,7 +220,7 @@ export const pythonFromBlock = function (
   generator: ExtendedPythonGenerator,
 ) {
   let code = 'def steps(self):\n';
-  code += generator.INDENT + 'if not hasattr(self, "_initialized_steps"):\n';
+  code += generator.INDENT + 'if not hasattr(self, \'_initialized_steps\'):\n';
   code += generator.INDENT.repeat(2) + 'self._current_step = \'' + block.mrcStepNames[0] + '\'\n';
   code += generator.INDENT.repeat(2) + 'self._initialized_steps = True\n\n';
   code += generator.INDENT + 'if self._current_step == None:\n';