setup: add missing pyyaml to setup.py and README.md

Change-Id: I1d35f38b17a315dd58e8dd91a27bfa6c2c85905d
diff --git a/setup.py b/setup.py
index 17edad9..930ba15 100644
--- a/setup.py
+++ b/setup.py
@@ -17,6 +17,7 @@
         "construct >= 2.9.51",
         "bidict",
         "gsm0338",
+        "pyyaml >= 5.1"
         "termcolor",
         "colorlog",
         "pycryptodome"