Fix government feed route type
Fix government feed route type

This should be an exact route. When requests are made for sub-resources
of this route, it results in a 500 from the taxons controller in Collections.

Running this rake task updates the existing routes and fixes the problem.
I thought that I might have to write a migration somewhere, but it seems not.

The `/courts-tribunals` route looks like it might also be ripe for an exact route
now, because the individual pages are rendered by collections. I'm not feeling
super-confident about it right now (without more investigation), and it doesn't
seem to be causing any problems, so I'll ignore it for now.

Resolves https://sentry.io/organizations/govuk/issues/1425303152/?project=202213&query=is%3Aunresolved

alphagov/whitehall,alphagov/whitehall,alphagov/whitehall,alphagov/whitehall