Skip pgmq/redis lazy-import tests when their extras are not installed

``test_pgmq_bus_lazy_import`` and ``test_redis_bus_lazy_import``
import ``pipecat.bus.network.pgmq`` / ``redis`` directly, which raises
when the optional ``pgmq`` / ``redis`` packages are missing. Gate each
test with ``@unittest.skipUnless`` on a top-level probe of the
underlying package so they're skipped (not errored) in environments
without the extras. ``test_unknown_attribute_raises`` is unaffected.

tests/test_bus_network.py

@@ -10,14 +10,30 @@ import unittest
 
 import pipecat.bus.network as network
 
+try:
+    import pgmq  # noqa: F401
+
+    PGMQ_AVAILABLE = True
+except ImportError:
+    PGMQ_AVAILABLE = False
+
+try:
+    import redis  # noqa: F401
+
+    REDIS_AVAILABLE = True
+except ImportError:
+    REDIS_AVAILABLE = False
+
 
 class TestNetworkPackageLazyImports(unittest.TestCase):
+    @unittest.skipUnless(PGMQ_AVAILABLE, "pgmq extra not installed")
     def test_pgmq_bus_lazy_import(self):
         """``PgmqBus`` is resolved on first attribute access."""
         from pipecat.bus.network.pgmq import PgmqBus as Direct
 
         self.assertIs(network.PgmqBus, Direct)
 
+    @unittest.skipUnless(REDIS_AVAILABLE, "redis extra not installed")
     def test_redis_bus_lazy_import(self):
         """``RedisBus`` is resolved on first attribute access."""
         from pipecat.bus.network.redis import RedisBus as Direct