uwsgi-python: adapt debian codename variable to standard scheme

uwsgi-python/tasks/apps/pgadmin4.yml

@@ -13,7 +13,7 @@
 - name: Enable Postgres APT repository
   apt_repository:
     # yamllint disable-line rule:line-length
-    repo: "deb https://apt.postgresql.org/pub/repos/apt/ {{ debian_version }}-pgdg main"
+    repo: "deb https://apt.postgresql.org/pub/repos/apt/ {{ ansible_distribution_release }}-pgdg main"
 
 - name: Debconf pgadmin4
   debconf:
@@ -35,7 +35,7 @@
   apt:
     name: python3-flaskext.wtf
     default_release: stretch-pgdg
-  when: debian_version == "stretch"
+  when: ansible_distribution_release == "stretch"
 
 - name: Fix directory permissions
   file: