PyYAML bug workaround

Change-Id: I7e4ba7e971f160e64837c067002ab9c98741eeb6
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 2d76d5b..640599e 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -163,7 +163,7 @@
     # via
     #   -r https://osm.etsi.org/gitweb/?p=osm/N2VC.git;a=blob_plain;f=requirements.txt;hb=paas
     #   pyrfc3339
-pyyaml==5.4.1
+pyyaml==5.3.1
     # via
     #   -r https://osm.etsi.org/gitweb/?p=osm/N2VC.git;a=blob_plain;f=requirements.txt;hb=paas
     #   -r https://osm.etsi.org/gitweb/?p=osm/common.git;a=blob_plain;f=requirements.txt;hb=paas