Fix error when migrating MySQL db (ref #393) (#573)

fix error when migrating MySQL db (ref #393)

db/migrate/20220609001128_rename_bulkrax_importer_run_to_importer_run.rb

@@ -1,7 +1,17 @@
 class RenameBulkraxImporterRunToImporterRun < ActiveRecord::Migration[5.2]
-  def change
+  def up
     if column_exists?(:bulkrax_pending_relationships, :bulkrax_importer_run_id)
+      remove_foreign_key :bulkrax_pending_relationships, :bulkrax_importer_runs
+      remove_index :bulkrax_pending_relationships, column: :bulkrax_importer_run_id
+
       rename_column :bulkrax_pending_relationships, :bulkrax_importer_run_id, :importer_run_id
+
+      add_foreign_key :bulkrax_pending_relationships, :bulkrax_importer_runs, column: :importer_run_id
+      add_index :bulkrax_pending_relationships, :importer_run_id, name: 'index_bulkrax_pending_relationships_on_importer_run_id'
     end
   end
+
+  def down
+    rename_column :bulkrax_pending_relationships, :importer_run_id, :bulkrax_importer_run_id
+  end
 end