filter-traceback: minimal change to make 3.13 happy

Python3.13 is including more context in the traceback for multi lines statement,
so we need to extend the filtering. This is the minimal change, but the next
changeset will do a larger change to convey where we effectively land

tests/filtertraceback.py

@@ -34,6 +34,9 for line in sys.stdin:
             # PEP 657: Fine-grained error locations in tracebacks
             #                       ~~~~~~^^^^^^^^^
             continue
+        elif line.startswith(' '):
+            # Python 3.13 provide de full statement context
+            continue
 
     elif state == 'file':
         # Ignore one line after "  File ", but sometimes "File" lines are