PyYAML fix

Change-Id: I34831d4559a1d17f75676a768ada5cad558e8a7e
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index e8e68cb..11e7285 100644
--- a/requirements.in
+++ b/requirements.in
@@ -33,5 +33,5 @@
 -r RO-VIM-vmware/requirements.in
 -r RO-VIM-gcp/requirements.in
 
-pyyaml==5.3.1
+pyyaml>6
 protobuf<4 # Required by Juju