appveyor pgsql update (#2119)

Author: mgravell

appveyor.yml

@@ -12,7 +12,7 @@ skip_commits:
 environment:
   Appveyor: true
   # Postgres
-  POSTGRES_PATH: C:\Program Files\PostgreSQL\9.6
+  POSTGRES_PATH: C:\Program Files\PostgreSQL\13
   PGUSER: postgres
   PGPASSWORD: Password12!
   POSTGRES_ENV_POSTGRES_USER: postgres
@@ -32,7 +32,7 @@ environment:
 
 services:
   # - mysql
-  - postgresql
+  - postgresql13
 
 init:
   - git config --global core.autocrlf input