Ensure alternatate email label links to select

The accessibility audit covered labels linking correctly to inputs/selects.
This label came back as not working correctly. This is due to the for
value not being the same as the selects id.

app/views/admin/editions/_accessible_attachment_field.html.erb

@@ -1,7 +1,7 @@
 <div class="govuk-!-margin-bottom-6">
   <% if edition.respond_to?(:alternative_format_provider) %>
     <div class="govuk-form-group gem-c-select">
-      <label class="govuk-label govuk-label--m govuk-!-font-weight-bold" for="alternative_format_provider_id">
+      <label class="govuk-label govuk-label--m govuk-!-font-weight-bold" for="edition_alternative_format_provider_id">
         Email address for ordering attachment files in an alternative format <%= "(required)" if edition.alternative_format_provider_required? %>
       </label>