Python: Minor refactor

A bit too much copy paste 😄

Author: RasmusWL

python/ql/test/library-tests/frameworks/jmespath/taint_test.py

@@ -1,6 +1,6 @@
 import jmespath
 
-def test_idna():
+def test_taint():
     data = TAINTED_DICT
 
     expression = jmespath.compile("foo.bar")