Remove deprecated version and upgrade Alpine to 3.21

Author: TrafeX

docker-compose.test.yml

@@ -1,10 +1,9 @@
-version: '3.5'
 services:
   app:
     image: ${IMAGE_NAME}:${IMAGE_TAG}
     build: .
   sut:
-    image: alpine:3.13
+    image: alpine:3.21
     depends_on:
       - app
     command: /tmp/run_tests.sh