diff --git a/tests/integration/test_boto3.py b/tests/integration/test_boto3.py
index 85ec59fa..cff712a8 100644
--- a/tests/integration/test_boto3.py
+++ b/tests/integration/test_boto3.py
@@ -83,7 +83,6 @@ def test_boto_vendored_stubs(tmpdir):
     "https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions",
 )
 def test_boto_medium_difficulty(tmpdir, get_user):
-
     with vcr.use_cassette(str(tmpdir.join("boto3-medium.yml"))):
         response = get_user()
         assert response["User"]["UserName"] == IAM_USER_NAME
diff --git a/tests/integration/test_matchers.py b/tests/integration/test_matchers.py
index 93d61b16..488eb8da 100644
--- a/tests/integration/test_matchers.py
+++ b/tests/integration/test_matchers.py
@@ -36,7 +36,6 @@ def cassette(tmpdir, httpbin, httpbin_secure):
     ],
 )
 def test_matchers(httpbin, httpbin_secure, cassette, matcher, matching_uri, not_matching_uri):
-
     matching_uri = _replace_httpbin(matching_uri, httpbin, httpbin_secure)
     not_matching_uri = _replace_httpbin(not_matching_uri, httpbin, httpbin_secure)
     default_uri = _replace_httpbin(DEFAULT_URI, httpbin, httpbin_secure)
@@ -76,7 +75,6 @@ def test_method_matcher(cassette, httpbin, httpbin_secure):
     "uri", [DEFAULT_URI, "http://httpbin.org/get?p2=q2&p1=q1", "http://httpbin.org/get?p2=q2&p1=q1"]
 )
 def test_default_matcher_matches(cassette, uri, httpbin, httpbin_secure):
-
     uri = _replace_httpbin(uri, httpbin, httpbin_secure)
 
     with vcr.use_cassette(cassette) as cass:
diff --git a/tests/unit/test_request.py b/tests/unit/test_request.py
index 54e82c1a..b29baa2f 100644
--- a/tests/unit/test_request.py
+++ b/tests/unit/test_request.py
@@ -60,7 +60,6 @@ def test_uri(method, uri):
 
 
 def test_HeadersDict():
-
     # Simple test of CaseInsensitiveDict
     h = HeadersDict()
     assert h == {}
diff --git a/tests/unit/test_vcr_import.py b/tests/unit/test_vcr_import.py
index 5872010a..e3a8c60d 100644
--- a/tests/unit/test_vcr_import.py
+++ b/tests/unit/test_vcr_import.py
@@ -2,7 +2,6 @@
 
 
 def test_vcr_import_deprecation(recwarn):
-
     if "vcr" in sys.modules:
         # Remove imported module entry if already loaded in another test
         del sys.modules["vcr"]
diff --git a/tox.ini b/tox.ini
index a3f2ed6c..6c2d555c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -40,7 +40,7 @@ commands =
     isort --version
     isort . --check --diff
     flake8 --version
-    flake8 --exclude=./docs/conf.py,./.tox/
+    flake8 --exclude=./docs/conf.py,./.tox/,./venv/
     pyflakes ./docs/conf.py
 deps =
   flake8
@@ -75,6 +75,8 @@ basepython = python3.7
 usedevelop=true
 commands =
     ./runtests.sh --cov=./vcr --cov-branch --cov-report=xml --cov-append {posargs}
+allowlist_externals =
+    ./runtests.sh
 deps =
     Werkzeug==2.0.3
     pytest
@@ -83,8 +85,9 @@ deps =
     PyYAML
     ipaddress
     requests: requests>=2.22.0
+    requests: urllib3<2
     httplib2: httplib2
-    urllib3: urllib3
+    urllib3: urllib3<2
     boto3: boto3
     boto3: urllib3
     aiohttp: aiohttp
diff --git a/vcr/patch.py b/vcr/patch.py
index 9399e3b7..a283287f 100644
--- a/vcr/patch.py
+++ b/vcr/patch.py
@@ -199,7 +199,6 @@ def _requests(self):
 
     @_build_patchers_from_mock_triples_decorator
     def _boto3(self):
-
         try:
             # botocore using awsrequest
             import botocore.awsrequest as cpool
diff --git a/vcr/stubs/compat.py b/vcr/stubs/compat.py
index d72218f0..bac79d8f 100644
--- a/vcr/stubs/compat.py
+++ b/vcr/stubs/compat.py
@@ -12,7 +12,7 @@ def get_header(message, name):
 
 
 def get_header_items(message):
-    for (key, values) in get_headers(message):
+    for key, values in get_headers(message):
         for value in values:
             yield key, value
 
diff --git a/vcr/stubs/httplib2_stubs.py b/vcr/stubs/httplib2_stubs.py
index fd126833..66cb0d29 100644
--- a/vcr/stubs/httplib2_stubs.py
+++ b/vcr/stubs/httplib2_stubs.py
@@ -28,7 +28,6 @@ class VCRHTTPSConnectionWithTimeout(VCRHTTPSConnection, HTTPSConnectionWithTimeo
     _baseclass = HTTPSConnectionWithTimeout
 
     def __init__(self, *args, **kwargs):
-
         # Delete the keyword arguments that HTTPSConnection would not recognize
         safe_keys = {
             "host",