Set an upper limit on the urllib3 dependency

With urllib3 2.4.0 stricter certificate validity checks were added when running
on Python 3.13+: urllib3/urllib3#3571.

This triggers errors such as the following:

> [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: Missing Authority
> Key Identifier

It is however only for users with Kubernetes clusters that have been set up
without proper, valid certificates. Notably, this was the case for AWS EKS
clusters created with Kubernetes v1.16 and earlier.

Author: Tenzer

requirements.txt

@@ -7,5 +7,5 @@ google-auth>=1.0.1  # Apache-2.0
 websocket-client>=0.32.0,!=0.40.0,!=0.41.*,!=0.42.* # LGPLv2+
 requests # Apache-2.0
 requests-oauthlib # ISC
-urllib3>=1.24.2  # MIT
+urllib3>=1.24.2,<2.4.0  # MIT
 durationpy>=0.7 # MIT