Update version of PyYAML

Change-Id: I6c5e0ddff419762edaf663c1d64e1e6cc155dd3d
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index ba3b6de..49848cd 100644
--- a/requirements.in
+++ b/requirements.in
@@ -20,6 +20,6 @@
 packaging
 prettytable
 python-magic
-pyyaml==5.4.1
+pyyaml>6
 requests
 verboselogs