refactor: consolidate urllib3 version constraints into single global requirement

Author: ahnv

requirements/requirements.txt

@@ -1,13 +1,11 @@
 requests_toolbelt>=1.0.0
+urllib3<3
 
 # ------------ Python >= 3.9 ------------
 requests>=2.32.2; python_version >= "3.9"
-urllib3<3; python_version >= "3.9"
 
 # ------------ 3.7 <= Python < 3.9 ------------
 requests>=2.22.0,<2.32; python_version >= "3.7" and python_version < "3.9"
-urllib3<2; python_version >= "3.7" and python_version < "3.9"
 
 # ------------ Python < 3.7 ------------
-requests>=2.22.0,<2.28; python_version < "3.7"
-urllib3<2; python_version < "3.7"
+requests>=2.22.0,<2.28; python_version < "3.7"

requirements/test.txt

@@ -1,19 +1,17 @@
 requests_toolbelt>=1.0.0
+urllib3<3
 
 # ------------ Python >= 3.9 ------------
 requests>=2.32.2; python_version >= "3.9"
-urllib3<3; python_version >= "3.9"
 coverage>=7.6.0; python_version >= "3.13"
 coverage>=7.5.0; python_version >= "3.9" and python_version < "3.13"
 
 # ------------ 3.7 <= Python < 3.9 ------------
 requests>=2.22.0,<2.32; python_version >= "3.7" and python_version < "3.9"
-urllib3<2; python_version >= "3.7" and python_version < "3.9"
 coverage>=5.0,<7.0; python_version >= "3.7" and python_version < "3.9"
 
 # ------------ Python < 3.7 ------------
 requests>=2.22.0,<2.28; python_version < "3.7"
-urllib3<2; python_version < "3.7"
 coverage==4.5.4; python_version < "3.7"
 
 # ------------ responses versions ------------