fix: drop schema specifier when enabling pgmq (#4391)

Author: sweatybridge

pkg/migration/scripts/dump_schema.sh

@@ -48,6 +48,7 @@ pg_dump \
 | sed -E "s/^REVOKE (.+) ON (.+) \"(${EXCLUDED_SCHEMAS:-})\"/-- &/" \
 | sed -E 's/^(CREATE EXTENSION IF NOT EXISTS "pg_tle").+/\1;/' \
 | sed -E 's/^(CREATE EXTENSION IF NOT EXISTS "pgsodium").+/\1;/' \
+| sed -E 's/^(CREATE EXTENSION IF NOT EXISTS "pgmq").+/\1;/' \
 | sed -E 's/^COMMENT ON EXTENSION (.+)/-- &/' \
 | sed -E 's/^CREATE POLICY "cron_job_/-- &/' \
 | sed -E 's/^ALTER TABLE "cron"/-- &/' \