[py] Correct dependency for six

Author: AutomatedTester

py/BUILD.bazel

@@ -196,6 +196,7 @@ py_test_suite(
         requirement("pytest-instafail"),
         requirement("pytest-mock"),
         requirement("pytest-trio"),
+        requirement("six"),
         requirement("sortedcontainers"),
         requirement("sniffio"),
         requirement("zipp"),

py/requirements.txt

@@ -16,6 +16,7 @@ pytest==6.1.2
 pytest-instafail==0.4.2
 pytest-mock==3.3.1
 pytest-trio==0.7.0
+six
 sortedcontainers
 sniffio
 trio==0.17.0