Update version of PyYAML

Change-Id: Ib51829e23f41e87451a53838af0f0ca4437144aa
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index 67d3cfe..cdcdafc 100644
--- a/requirements.in
+++ b/requirements.in
@@ -20,6 +20,6 @@
 grpclib
 idna
 jinja2
-pyyaml==5.4.1
+pyyaml>6
 pydantic
 protobuf==3.20.3