Bump up flask version

Change-Id: I2a7363f99d88cf9feaf26169f5ce1cd67156927a
diff --git a/requirements.txt b/requirements.txt
index 8b5440e..f7f567d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -3,7 +3,7 @@
 # SPDX-FileCopyrightText: 2020-present Open Networking Foundation <info@opennetworking.org>
 # SPDX-License-Identifier: Apache-2.0
 #
-Flask==2.0.3
+Flask==2.2.2
 prometheus_client==0.14.1
 pyaml==21.10.1
 requests==2.22.0
\ No newline at end of file