Bump minimum required version of PyYAML (#81)

Author: David Robertson

setup.py

@@ -1,6 +1,6 @@
 from setuptools import setup
 
-__version__ = "1.1.1" 
+__version__ = "1.1.2"
 
 with open("README.md") as f:
     long_description = f.read()
@@ -25,7 +25,7 @@
         "botocore>=1.12.23,<2.0",
         "humanize>=0.5.1,<0.6",
         "psycopg2>=2.7.5,<3.0",
-        "PyYAML>=3.13,<4.0",
+        "PyYAML>=5.4,<6.0",
         "tqdm>=4.26.0,<5.0",
         "Twisted",
     ],