Add 'paused' label to 'prefect_info_deployments' metric (#47)

* Add 'paused' label to 'prefect_info_deployments' metric

- Adds the 'paused' label to the 'prefect_info_deployments' metric
- Also uses this value for the 'is_schedule_active' label, which is
  deprecated and always returns Null.
- Updates the docker-compose testing setup to use Prefect 3

Related to PLA-224

* Negate the 'paused' value for 'is_schedule_active'

'is_schedule_active' is the opposite of 'paused', so if we're using the
'paused' value we need to negate it.

* Fix null case

* Fix logic for negating value

If we get "null" back, we don't want to `not` that because we'll always
get False instead of "null". This separates the logic and only negates
the value if we don't get "null" back.

compose.yml

@@ -1,6 +1,6 @@
 services:
   prefect:
-    image: prefecthq/prefect:2-latest
+    image: prefecthq/prefect:3-latest
     ports:
       - "4200:4200"
     environment:

metrics/metrics.py

@@ -102,6 +102,7 @@ def collect(self):
                 "is_schedule_active",
                 "deployment_name",
                 "path",
+                "paused",
                 "work_pool_name",
                 "work_queue_name",
                 "status",
@@ -122,15 +123,25 @@ def collect(self):
                     "null",
                 )
 
+            # The "is_schedule_active" field is deprecated, and always returns
+            # "null". For backward compatibility, we will populate the value of
+            # this label with the "paused" field.
+            is_schedule_active = deployment.get("paused", "null")
+            if is_schedule_active != "null":
+                # Negate the value we get from "paused" because "is_schedule_active"
+                # is the opposite of "paused".
+                is_schedule_active = not is_schedule_active
+
             prefect_info_deployments.add_metric(
                 [
                     str(deployment.get("created", "null")),
                     str(deployment.get("flow_id", "null")),
                     str(flow_name),
                     str(deployment.get("id", "null")),
-                    str(deployment.get("is_schedule_active", "null")),
+                    str(is_schedule_active),
                     str(deployment.get("name", "null")),
                     str(deployment.get("path", "null")),
+                    str(deployment.get("paused", "null")),
                     str(deployment.get("work_pool_name", "null")),
                     str(deployment.get("work_queue_name", "null")),
                     str(deployment.get("status", "null")),