Update version of PyYAML

Change-Id: Ibe3a0203e90e90cdbb54808abc8e46832702f498
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
(cherry picked from commit 32f92ce2d3df9e66686cebe499a51c0964c23acb)
diff --git a/requirements.txt b/requirements.txt
index ee2bcae..89c705f 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -265,7 +265,7 @@
     # via tzlocal
 pyvcloud==23.0.4
     # via -r requirements.in
-pyyaml==5.4.1
+pyyaml==6.0.1
     # via
     #   -r requirements.in
     #   cliff