Permits ERB syntax in downloads.yml file

[sjproctor]

This commit fixes the malformed format string - %= error that occurs when ERB syntax is used in the downloads.yml file.

[corylown]

Hi @sjproctor -- can you say a bit more about why this change is needed? The current downloads.yml pattern is to use %{} syntax that will evaluate accessor methods set on SolrDocument. What's the use case that this pattern doesn't cover?

[sjproctor]

Hi @sjproctor -- can you say a bit more about why this change is needed? The current downloads.yml pattern is to use %{} syntax that will evaluate accessor methods set on SolrDocument. What's the use case that this pattern doesn't cover?

Hi there. I am looking to use an environment variable in the yml file. The ERB tags are causing an error.

[corylown]

@sjproctor I think CI was not working when you made this pull request. Can you rebase from the latest main? and if the tests pass this looks okay to me.