Refactor DownloadLinkMailer

When we attempted to update to a new version of Ruby, this Mailer
stopped working.

We are not sure why, but switching to positional arguments resolves the
issue, UserMailer uses positional arguments so we assume that this is
acceptable.

Making this refactor opens the door to update Ruby.

app/jobs/spending_breakdown_job.rb

@@ -13,12 +13,12 @@ def perform(requester_id:, fund_id:)
     fund_activity.save!
 
     DownloadLinkMailer.send_link(
-      recipient: requester,
-      file_name: upload.timestamped_filename
+      requester,
+      upload.timestamped_filename
     ).deliver
   rescue => error
     log_error(error, requester)
-    DownloadLinkMailer.send_failure_notification(recipient: requester).deliver
+    DownloadLinkMailer.send_failure_notification(requester).deliver
   end
 
   def save_tempfile(export)

app/mailers/download_link_mailer.rb

@@ -1,5 +1,5 @@
 class DownloadLinkMailer < ApplicationMailer
-  def send_link(recipient:, file_name:)
+  def send_link(recipient, file_name)
     @file_name = file_name
     @file_url = exports_url
 
@@ -15,7 +15,7 @@ def send_link(recipient:, file_name:)
     )
   end
 
-  def send_failure_notification(recipient:)
+  def send_failure_notification(recipient)
     view_mail(
       ENV["NOTIFY_VIEW_TEMPLATE"],
       to: recipient.email,

spec/jobs/spending_breakdown_job_spec.rb

@@ -127,7 +127,7 @@
 
         expect(DownloadLinkMailer)
           .to have_received(:send_failure_notification)
-          .with(recipient: requester)
+          .with(requester)
         expect(email).to have_received(:deliver)
       end
     end
@@ -136,8 +136,8 @@
       SpendingBreakdownJob.perform_now(requester_id: double, fund_id: double)
 
       expect(DownloadLinkMailer).to have_received(:send_link).with(
-        recipient: requester,
-        file_name: "timestamped_filename.csv"
+        requester,
+        "timestamped_filename.csv"
       )
       expect(email).to have_received(:deliver)
     end

spec/mailers/download_link_mailer_spec.rb

@@ -6,8 +6,8 @@
   describe "#send_link(recipient:, file_url:, file_name:)" do
     let(:mail) do
       DownloadLinkMailer.send_link(
-        recipient: user,
-        file_name: "spending_breakdown.csv"
+        user,
+        "spending_breakdown.csv"
       )
     end
 
@@ -72,7 +72,7 @@
 
   describe "#send_failure_notification(recipient:)" do
     let(:mail) do
-      DownloadLinkMailer.send_failure_notification(recipient: user)
+      DownloadLinkMailer.send_failure_notification(user)
     end
 
     it "sends the email to the given recipient" do