Make export of migrations False by default (#313)

Co-authored-by: kwabena <[email protected]>

Author: kaypee90

django_prometheus/apps.py

@@ -20,5 +20,5 @@ def ready(self):
         are usually short-lived), but can be useful for debugging.
         """
         SetupPrometheusExportsFromConfig()
-        if getattr(settings, "PROMETHEUS_EXPORT_MIGRATIONS", True):
+        if getattr(settings, "PROMETHEUS_EXPORT_MIGRATIONS", False):
             ExportMigrations()