chore: adding contentType in post and put (#796)

* chore: adding contentType in post and put

Author: tiwarishubham635

twilio/base/client_base.py

@@ -184,7 +184,7 @@ def get_headers(
 
         # Types, encodings, etc.
         headers["Accept-Charset"] = "utf-8"
-        if method == "POST" and "Content-Type" not in headers:
+        if (method == "POST" or method == "PUT") and ("Content-Type" not in headers):
             headers["Content-Type"] = "application/x-www-form-urlencoded"
         if "Accept" not in headers:
             headers["Accept"] = "application/json"