PyYAML bug workaround

Change-Id: Ifecf6be5c7f93b1a7f519b353906c7d70660832b
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index 12fce5b..d5c0bcd 100644
--- a/requirements.in
+++ b/requirements.in
@@ -15,6 +15,6 @@
 deepdiff
 jsonschema>=3.2.0
 python-keystoneclient
-pyyaml==5.4.1
+pyyaml==5.3.1
 requests
 tacacs_plus