Add guard to uploaded_files migration (#994)

* Add guard to uploaded_files migration

This commit will check if uploaded_files is a table before adding the
file_name column to it.  In a Hydra application, it is not so this was
crashing.

* Update db/migrate/20240806161142_add_file_name_to_uploaded_files.rb

Co-authored-by: Rob Kaufman <[email protected]>

---------

Co-authored-by: Rob Kaufman <[email protected]>

db/migrate/20240806161142_add_file_name_to_uploaded_files.rb

@@ -1,5 +1,5 @@
 class AddFileNameToUploadedFiles < ActiveRecord::Migration[5.2]
   def change
-    add_column :uploaded_files, :filename, :string unless column_exists?(:uploaded_files, :filename)
+    add_column :uploaded_files, :filename, :string if table_exists?(:uploaded_files) && !column_exists?(:uploaded_files, :filename)
   end
 end