Add Redis Cluster instrumentation support (#844)

* Use Job.id property instead of removed get_id() method

rq v2.7 refactored Job.id from `id = property(get_id, set_id)` to a
`@property` decorator, removing get_id() as a callable method.
Job.id has been available since rq v0.5.0 so this is backwards compatible.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Support FastMCP 3.x while maintaining 2.x backwards compatibility

FastMCP 3.0 replaced private _call_tool_mcp()/_list_tools_mcp() with
public call_tool()/list_tools() methods, and changed get_tool() to
return None instead of raising when a tool is not found.

- Update instrumentation to handle get_tool() returning None
- Update tests with compat helpers that use the correct API based on
  the installed fastmcp version
- Remove the fastmcp<3 version pin from tox.ini (no longer needed)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* Add Redis Cluster instrumentation support

Extend Redis instrumentation to cover RedisCluster.execute_command()
when available, providing visibility into cluster operations including
the new async Cluster PubSub feature in redis-py.

Closes #840

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: mitchh456

src/scout_apm/instruments/redis.py

@@ -18,15 +18,22 @@
         from redis import StrictRedis as Redis
         from redis.client import BasePipeline as Pipeline
 
+    try:
+        from redis.cluster import RedisCluster
+    except ImportError:
+        RedisCluster = None
+
 logger = logging.getLogger(__name__)
 
 
 have_patched_redis_execute_command = False
 have_patched_pipeline_execute = False
+have_patched_redis_cluster_execute_command = False
 
 
 def ensure_installed():
     global have_patched_redis_execute_command, have_patched_pipeline_execute
+    global have_patched_redis_cluster_execute_command
 
     logger.debug("Instrumenting redis.")
 
@@ -55,6 +62,20 @@ def ensure_installed():
             else:
                 have_patched_pipeline_execute = True
 
+        if RedisCluster is not None and not have_patched_redis_cluster_execute_command:
+            try:
+                RedisCluster.execute_command = wrapped_execute_command(
+                    RedisCluster.execute_command
+                )
+            except Exception as exc:
+                logger.warning(
+                    "Failed to instrument redis.RedisCluster.execute_command: %r",
+                    exc,
+                    exc_info=exc,
+                )
+            else:
+                have_patched_redis_cluster_execute_command = True
+
     return True