Patch dparse locally - remove top level yaml import

We don't use this yaml import (only used for conda file parsing).
Hence, we can remove this.

tasks/vendoring/patches/vendor/dparse-local-yaml.patch

@@ -0,0 +1,20 @@
+diff --git a/dparse/parser.py b/dparse/parser.py
+index c01ebab..18689a5 100644
+--- a/pipenv/vendor/dparse/parser.py
++++ b/pipenv/vendor/dparse/parser.py
+@@ -2,7 +2,6 @@
+ from __future__ import unicode_literals, absolute_import
+ from collections import OrderedDict
+ import re
+-import yaml
+ 
+ from io import StringIO
+ 
+@@ -301,6 +300,7 @@ class CondaYMLParser(Parser):
+ 
+         :return:
+         """
++        import yaml
+         try:
+             data = yaml.safe_load(self.obj.content)
+             if data and 'dependencies' in data and isinstance(data['dependencies'], list):