Fix bad error message on import for unknown pages (#1287)

A long time back, we did a lot of cleanup of the field names for pages, versions, and the format of import records. However, this error message apparently never got updated! I noticed some warnings today with messages that didn't make any sense, and this was the cause.

Author: Mr0grog

app/jobs/import_versions_job.rb

@@ -71,7 +71,7 @@ def import_record(record, row)
     record = normalize_record(record)
     page = page_for_record(record, create: @import.create_pages, row:)
     unless page
-      warn "Skipped unknown URL: #{record['page_url']}@#{record['capture_time']}"
+      warn "Skipped unknown URL: #{record['url']}@#{record['capture_time']}"
       return
     end
     unless page.active?