Bump requests minimum bound to 2.18.0 (googleapis#3748)

Author: lukesneeringer

bigquery/setup.py

@@ -54,7 +54,7 @@
     'google-cloud-core >= 0.26.0, < 0.27dev',
     'google-auth >= 1.0.0',
     'google-resumable-media >= 0.2.1',
-    'requests >= 2.0.0',
+    'requests >= 2.18.0',
 ]
 
 setup(

core/setup.py

@@ -54,7 +54,7 @@
     'googleapis-common-protos >= 1.3.4',
     'protobuf >= 3.0.0',
     'google-auth >= 0.4.0, < 2.0.0dev',
-    'requests >= 2.4.0, < 3.0.0dev',
+    'requests >= 2.18.0, < 3.0.0dev',
     'setuptools >= 34.0.0',
     'six',
     'tenacity >= 4.0.0, <5.0.0dev'

storage/setup.py

@@ -54,7 +54,7 @@
     'google-cloud-core >= 0.26.0, < 0.27dev',
     'google-auth >= 1.0.0',
     'google-resumable-media >= 0.2.3',
-    'requests >= 2.0.0',
+    'requests >= 2.18.0',
 ]
 
 setup(