add pytz to test-requirements.txt

Author: notque

test-requirements.txt

@@ -11,6 +11,7 @@ coverage!=4.4,>=4.0 # Apache-2.0
 fixtures>=3.0.0 # Apache-2.0/BSD
 mock>=3.0.0 # BSD
 oslotest>=3.8.0 # Apache-2.0
+pytz==2025.1 # MIT
 requests-mock>=1.2.0 # Apache-2.0
 #stevedore>=1.20.0 # Apache-2.0
 stestr>=2.0.0  # Apache-2.0