Update version of PyYAML

Change-Id: I2c53f1ffa67ec6cbda483e839be2778f185100a9
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
(cherry picked from commit 7aad5a5da15c7b5d6c4d87f27fc0cc59c3ce5e79)
diff --git a/requirements.txt b/requirements.txt
index 3782aed..f6f3d14 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -34,5 +34,5 @@
     # via
     #   -r requirements.in
     #   motor
-pyyaml==5.4.1
+pyyaml==6.0.1
     # via -r requirements.in