[FIX] tests: avoid traceback when websocket-client is not installed

The account module needs to import Form from "tests.common" causing a
traceback when websocket-client module is not installed.

As this module is only required for the tests, there is no reason to add
it to the "requirements.txt" file.

With this commit, Odoo account can be installed even when
websocket-client is not installed, in that case, the HttpCase tests that
needs to run Chrome headless will be skipped with a warning.

Closes: #26404

odoo/tests/common.py

@@ -25,7 +25,6 @@ import tempfile
 import threading
 import time
 import unittest
-import websocket
 import werkzeug.urls
 from contextlib import contextmanager
 from datetime import datetime, timedelta, date
@@ -43,6 +42,13 @@ try:
     from itertools import zip_longest as izip_longest
 except ImportError:
     from itertools import izip_longest
+
+try:
+    import websocket
+except ImportError:
+    # chrome headless tests will be skipped
+    websocket = None
+
 try:
     from xmlrpc import client as xmlrpclib
 except ImportError:
@@ -399,6 +405,9 @@ class SavepointCase(SingleTransactionCase):
 class ChromeBrowser():
 
     def __init__(self):
+        if websocket is None:
+            _logger.warning("websocket-client module is not installed")
+            raise unittest.SkipTest("websocket-client module is not installed")
         self.devtools_port = PORT + 2
         self.ws_url = ''  # WebSocketUrl
         self.ws = None  # websocket