Fix flake8 error

Forgot to rename one var...

pre_commit_hooks/requirements_txt_fixer.py

diff --git a/pre_commit_hooks/requirements_txt_fixer.py b/pre_commit_hooks/requirements_txt_fixer.py
index 135fe2e..6dcf8d0 100644
--- a/pre_commit_hooks/requirements_txt_fixer.py
+++ b/pre_commit_hooks/requirements_txt_fixer.py
@@ -72,8 +72,8 @@
     # find and remove pkg-resources==0.0.0
     # which is automatically added by broken pip package under Debian
     requirements = [
-        requirement for requirement in requirements
-        if requirement.value != b'pkg-resources==0.0.0\n'
+        req for req in requirements
+        if req.value != b'pkg-resources==0.0.0\n'
     ]
 
     for requirement in sorted(requirements):