Add version script to pgstac initialization script.

This adds the entry to the migrations table which was missing prior,
and would cause "pypgstac migrate" to fail on new databases

Author: lossyrob

pgstac.sql

@@ -3,4 +3,5 @@ BEGIN;
 \i sql/002_collections.sql
 \i sql/003_items.sql
 \i sql/004_search.sql
+\i sql/999_version.sql
 COMMIT;