Note this version includes Bundler 2, so we can finally upgrade.

We were getting hundreds of "warning: URI.escape is obsolete" messages.
So we're using `URI::DEFAULT_PARSER.escape` instead.

IMHO it's OK to add this monkey-patch because we're replacing Paperclip
with Active Storage, and when we finish with that we'll delete this
file.

I think we could have already done so when upgrading Ruby to version
2.6.x (which also included the Bundler gem), but since we didn't, now
that we've upgraded to Bundler 2.x it's probably a good moment.