Python 3.6 updates

Author: Anthchirp

.azure-pipelines/syntax-validation.py

@@ -12,7 +12,7 @@
             continue
         filename = os.path.normpath(os.path.join(base, f))
         try:
-            with open(filename, "r") as fh:
+            with open(filename) as fh:
                 ast.parse(fh.read())
         except SyntaxError as se:
             failures += 1

procrunner/__init__.py

@@ -333,7 +333,7 @@ def __getitem__(self, key):
         if key in self._extras:
             return self._extras[key]
         if not hasattr(self, key):
-            raise KeyError("Unknown attribute {key}".format(key=key))
+            raise KeyError(f"Unknown attribute {key}")
         return getattr(self, key)
 
     def __eq__(self, other):