Add the action of decryption for the gamma cipher.

src/cipher_analytical_machine/cli/actions/cryptography.clj

@@ -49,7 +49,9 @@
     (cond
       (= action-type :encrypt)
       (gamma/encrypt-message key symbols message)
-      )))
+
+      (= action-type :decrypt)
+      (gamma/decrypt-message key symbols message))))
 
 (defn cryptography-actions
   [options arguments action-type]