Don't try and parse t-string syntax from withdrawn PEP

Author: hugovk

peps/pep-0501.rst

@@ -1326,7 +1326,7 @@ The approach to standardising lazy field evaluation described in this PEP is
 primarily based on the anticipated needs of this hypothetical integration into
 the logging module:
 
-.. code-block:: python
+.. code-block:: text
 
     logging.debug(t"Eager evaluation of {expensive_call()}")
     logging.debug(t"Lazy evaluation of {expensive_call!()}")