PyYAML fix

Change-Id: Icd71a982131353a03fa745ff7616ad657173e657
Signed-off-by: Mark Beierl <mark.beierl@canonical.com>
diff --git a/requirements.in b/requirements.in
index 9110808..71f1f9a 100755
--- a/requirements.in
+++ b/requirements.in
@@ -15,6 +15,6 @@
 # WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 # License for the specific language governing permissions and limitations
 # under the License.
-pyyaml==5.3.1
+pyyaml>6
 pymzn==0.18.*
 jinja2