Add signal extras and handle missing mock dependency

Missing dependency noted in https://github.com/NeonGeckoCom/neon_audio/actions/runs/13190248663/job/36821655199?pr=178

neon_utils/signal_utils.py

@@ -31,12 +31,16 @@
 from time import time, sleep
 from typing import Optional, Callable
 
-from mock.mock import Mock
 from ovos_bus_client import MessageBusClient, Message
 from ovos_utils.log import log_deprecation
 
 from neon_utils.logger import LOG
 
+try:
+    from mock.mock import Mock
+except ImportError:
+    raise ImportError("`mock` is not installed,"
+                      " pip install neon-utils[signal]")
 _BUS: Optional[MessageBusClient] = None
 _MAX_TIMEOUT: Optional[int] = None
 

requirements/signal.txt

@@ -0,0 +1 @@
+mock

setup.py

@@ -86,7 +86,8 @@ def get_requirements(requirements_filename: str):
         "audio": get_requirements("audio.txt"),
         "network": get_requirements("network.txt"),
         "configuration": get_requirements("configuration.txt"),
-        "sentry": get_requirements("sentry.txt")
+        "sentry": get_requirements("sentry.txt"),
+        "signal": get_requirements("signal.txt")
     },
     entry_points={
         'console_scripts': [