Pin pycodestyle version

Related-Bug: PRODX-22869
Change-Id: I80d0147c3e68450158b6562dc500b35f60dec81a
diff --git a/test-requirements.txt b/test-requirements.txt
index bf1c626..332cf77 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -14,3 +14,4 @@
 openstackdocstheme>=2.2.1 # Apache-2.0
 # releasenotes
 reno>=3.1.0 # Apache-2.0
+pycodestyle<2.7.0 # MIT