Clean up test imports per Copilot suggestion

Remove module-level sys.path manipulation from test files:
- test_browsergym_models.py: removed entirely (pytest handles imports)
- test_browsergym_environment.py: moved into server fixture where it's
  actually needed for subprocess environment

This is cleaner and follows pytest best practices.

Author: HamidShojanazeri

tests/envs/test_browsergym_environment.py

@@ -7,18 +7,16 @@
 import requests
 import pytest
 
-# Add src to path
-ROOT_DIR = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
-SRC_PATH = os.path.join(ROOT_DIR, "src")
-sys.path.insert(0, SRC_PATH)
-
 from envs.browsergym_env.client import BrowserGymEnv
 from envs.browsergym_env.models import BrowserGymAction
 
 
 @pytest.fixture(scope="module")
 def server():
     """Starts the BrowserGym environment server as a background process."""
+    # Define paths for subprocess environment
+    ROOT_DIR = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", ".."))
+    SRC_PATH = os.path.join(ROOT_DIR, "src")
     PORT = 8010
     localhost = f"http://localhost:{PORT}"
 

tests/envs/test_browsergym_models.py

@@ -1,9 +1,5 @@
 """Unit tests for BrowserGym models."""
 
-import os
-import sys
-
-
 from envs.browsergym_env.models import (
     BrowserGymAction,
     BrowserGymObservation,