Supress warnings in Paperclip::UrlGenerator

We were getting hundreds of "warning: URI.escape is obsolete" messages.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.

config/initializers/paperclip.rb

@@ -0,0 +1,13 @@
+class Paperclip::UrlGenerator
+  private
+
+    # Code copied from the paperclip gem, only replacing
+    # `URI.escape` with `URI::DEFAULT_PARSER.escape`
+    def escape_url(url)
+      if url.respond_to?(:escape)
+        url.escape
+      else
+        URI::DEFAULT_PARSER.escape(url).gsub(escape_regex) { |m| "%#{m.ord.to_s(16).upcase}" }
+      end
+    end
+end