Drop hard cap on lxml major version

plivo/utils/__init__.py

@@ -64,7 +64,7 @@ def is_valid_mainaccount(mainaccount):
 
 
 def to_param_dict(func, vals, exclude_none=True, func_args_check=True):
-    args, varargs, kwargs, _ = inspect.getargspec(func)
+    args, varargs, kwargs, _, _, _, _ = inspect.getfullargspec(func)
     arg_names = list(args)
     # The bit of regex magic below is for arguments that are keywords in
     # Python, like from. These can't be used directly, so our convention is to

setup.cfg

@@ -2,4 +2,5 @@
 universal = 1
 
 [metadata]
-description-file = README.md
+description = The Plivo Python SDK makes it simpler to integrate communications into your Python applications using the Plivo REST API. Using the SDK, you will be able to make voice calls, send SMS and generate Plivo XML to control your call flows.
+long_description = file: README.md

setup.py

@@ -38,7 +38,7 @@
         'requests >= 2, < 3',
         'six >= 1, < 2',
         'decorator >= 4, < 5',
-        'lxml >= 3, < 5',
+        'lxml >= 3',
     ],
     keywords=['plivo', 'plivo xml', 'voice calls', 'sms'],
     include_package_data=True,