Add requirements-txt-fixer pre-commit hook and run on all files

.pre-commit-config.yaml

@@ -15,3 +15,4 @@
     -   id: pretty-format-json
         args:
         - --autofix
+    -   id: requirements-txt-fixer

UPGRADE-v2.0.md

@@ -207,7 +207,7 @@ Before:
 ```python
 class SomeMutation(Mutation):
     ...
-    
+
     @classmethod
     def mutate(cls, instance, args, context, info):
         ...
@@ -218,7 +218,7 @@ With 2.0:
 ```python
 class SomeMutation(Mutation):
     ...
-    
+
     def mutate(self, info, **args):
         ...
 ```
@@ -231,7 +231,7 @@ class SomeMutation(Mutation):
         first_name = String(required=True)
         last_name = String(required=True)
     ...
-    
+
     def mutate(self, info, first_name, last_name):
         ...
 ```
@@ -250,7 +250,7 @@ If you are using Middelwares, you need to some adjustments:
 Before:
 
 ```python
-class MyGrapheneMiddleware(object):    
+class MyGrapheneMiddleware(object):  
     def resolve(self, next_mw, root, args, context, info):
 
         ## Middleware code
@@ -261,7 +261,7 @@ class MyGrapheneMiddleware(object):
 With 2.0:
 
 ```python
-class MyGrapheneMiddleware(object):    
+class MyGrapheneMiddleware(object):  
     def resolve(self, next_mw, root, info, **args):
         context = info.context
 

docs/requirements.txt

@@ -1,4 +1,4 @@
-# Required library
-Sphinx==1.5.3
 # Docs template
 http://graphene-python.org/sphinx_graphene_theme.zip
+# Required library
+Sphinx==1.5.3