Update version of PyYAML

Change-Id: Ib65a9712db84ea4346fdea11c5554845dc2d52ec
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index c083f65..6cdf466 100644
--- a/requirements.in
+++ b/requirements.in
@@ -16,7 +16,7 @@
 aiokafka
 peewee
 jsonschema
-pyyaml==5.4.1
+pyyaml>6
 pymysql
 peewee-migrate
 requests