chore(fix): update rating svc dependencies

upgrade uwsgi to 2.0.20
upgrade python runtime to 3.9

Author: minherz

src/ratingservice/requirements.txt

@@ -1,4 +1,4 @@
-uwsgi==2.0.19.1
+uwsgi==2.0.20
 flask==2.1.2
 psycopg2-binary==2.9.3
 google-python-cloud-debugger==2.18

terraform/ratingservice/04_appengine.tf

@@ -37,7 +37,7 @@ resource "google_app_engine_standard_app_version" "default" {
   project    =  var.gcp_project_id
   service    = "default"
   version_id = "v1"
-  runtime    = "python38"
+  runtime    = "python39"
 
   entrypoint {
     shell = "uwsgi --http-socket :8080 --wsgi-file main.py --callable app --master --processes 1 --threads 1"