Add automatic instrumentation to Postgres queries

This enables automatic instrumentation of Postgres queries when
OpenTelemetry instrumentation is enabled, which will help with debugging
performance problems.

bookwyrm/apps.py

@@ -40,6 +40,7 @@ class BookwyrmConfig(AppConfig):
             from bookwyrm.telemetry import open_telemetry
 
             open_telemetry.instrumentDjango()
+            open_telemetry.instrumentPostgres()
 
         if settings.ENABLE_PREVIEW_IMAGES and settings.FONTS:
             # Download any fonts that we don't have yet

bookwyrm/telemetry/open_telemetry.py

@@ -22,6 +22,12 @@ def instrumentDjango():
     DjangoInstrumentor().instrument()
 
 
+def instrumentPostgres():
+    from opentelemetry.instrumentation.psycopg2 import Psycopg2Instrumentor
+
+    Psycopg2Instrumentor().instrument()
+
+
 def instrumentCelery():
     from opentelemetry.instrumentation.celery import CeleryInstrumentor
     from celery.signals import worker_process_init