Change the secret message being checks in tests

Now that we are not overwriting the internal Python package file the
text we look for must match what is output by default. The Docker
Compose secret configuration is left in place to continue to serve as
an example and to be leveraged for a future update to
cisagov/skeleton-python-library that can provide similar functionality
to what was removed in this project.

tests/container_test.py

@@ -11,9 +11,7 @@
 ENV_VAR = "ECHO_MESSAGE"
 ENV_VAR_VAL = "Hello World from docker compose!"
 READY_MESSAGE = "This is a debug message"
-SECRET_QUOTE = (
-    "There are no secrets better kept than the secrets everybody guesses."  # nosec
-)
+SECRET_QUOTE = "Three may keep a secret, if two of them are dead."  # nosec
 RELEASE_TAG = os.getenv("RELEASE_TAG")
 VERSION_FILE = "src/version.txt"