setup: Bump min ruamel.yaml version to 0.15

Author: mbr0wn

pybombs/config_file.py

@@ -48,9 +48,7 @@ def __init__(self):
             self._load = self.yaml.load
             self._dump = self.yaml.dump
         else:
-            self.yaml = yaml
-            self._load = self.yaml.round_trip_load
-            self._dump = self.yaml.round_trip_dump
+            raise AssertionError("Invalid ruamel.yaml version")
 
     def load(self, fd):
         """Load contents of a file descriptor and return a dictionary."""

setup.py

@@ -97,7 +97,7 @@
     "requests",
     "six",
     "future",
-    "ruamel.yaml"
+    "ruamel.yaml >= 0.15.0",
 ]
 
 setup(