Add long secret test case (commented)

.env.sample

@@ -15,5 +15,6 @@ WITH_COMMENT=foo # should be removed
 SECRET_TEST_PASS_ONE_VERSION=v1
 SECRET_TEST_PASS_TWO_VERSION=v1 # length=10
 #SECRET_EXTRA_PASS_VERSION=v1
+#SECRET_LONG_SECRET_VERSION=v1
 
 NETWORK_WITH_COMMENT=BAZ # should be removed

compose.long_secret.yml

@@ -0,0 +1,12 @@
+---
+version: "3.8"
+
+services:
+  app:
+    secrets:
+      - long_secret
+
+secrets:
+  long_secret:
+    external: true
+    name: ${STACK_NAME}_long_secret1234567890_${SECRET_LONG_SECRET_VERSION}