Merge pull request #199 from pallets/dependabot/pip/urllib3-1.26.4

diff --git a/requirements/dev.txt b/requirements/dev.txt
index 218acf3..11413bc 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -117,7 +117,7 @@
     # via mypy
 typing-extensions==3.7.4.3
     # via mypy
-urllib3==1.26.3
+urllib3==1.26.4
     # via requests
 virtualenv==20.4.2
     # via
diff --git a/requirements/docs.txt b/requirements/docs.txt
index 2303671..1f7c3d9 100644
--- a/requirements/docs.txt
+++ b/requirements/docs.txt
@@ -60,7 +60,7 @@
     # via sphinx
 sphinxcontrib-serializinghtml==1.1.4
     # via sphinx
-urllib3==1.26.3
+urllib3==1.26.4
     # via requests
 
 # The following packages are considered to be unsafe in a requirements file: