text: Title: Fix typos in ```spec_evaluator.py```
  Body: File: [spec_evaluator.py](https://github.com/scanapi/scanapi/blob/main/scanapi/evaluators/spec_evaluator.py#L72)
  
  ```Python
      @classmethod
      def filter_response_var(cls, spec_vars):
          """Returns a copy pf ``spec_vars`` without 'response' references.
          Any items with a ``response.*`` reference in their value are left out.
          Returns:
              [dict]: filtered dictionary.
          """
          pattern = re.compile(r"(?:(\s*response\.\w+))")
          return {k: v for k, v in spec_vars.items() if not pattern.search(v)}
  ```
  
  Update docstring typo in the classmethod `Returns a copy pf` -> `Returns a copy of`  