try @testing-repo 4

applications/podman.sls

@@ -1,6 +1,3 @@
-include:
-  - system.apk
-
 applications_podman_pkgs:
   pkg.installed:
     - pkgs:
@@ -9,11 +6,8 @@ applications_podman_pkgs:
 
 application_podman_compose_pkg:
   pkg.installed:
-    - pkgs:
-      - podman-compose
-    - fromrepo: testing
-    - require:
-      - applications_podman_pkgs
+    - sources:
+      - podman-compose: https://dl-cdn.alpinelinux.org/alpine/edge/testing
 
 applications_podman_rootless_confd:
   file.keyvalue:

system/apk.sls

@@ -1,5 +0,0 @@
-system_apk_testing-repo:
-  pkgrepo.managed:
-    - name: https://dl-cdn.alpinelinux.org/alpine/edge/testing
-    - dist: testing
-    - file: /etc/apk/repositories