Add have_http_link_header matcher and set header values as strings (#31010)

spec/requests/api/v1/timelines/home_spec.rb

@@ -94,8 +94,9 @@ RSpec.describe 'Home', :inline_jobs do
       it 'returns http unprocessable entity', :aggregate_failures do
         subject
 
-        expect(response).to have_http_status(422)
-        expect(response.headers['Link']).to be_nil
+        expect(response)
+          .to have_http_status(422)
+          .and not_have_http_link_header
       end
     end
   end

spec/requests/api/v1/timelines/list_spec.rb

@@ -47,8 +47,9 @@ RSpec.describe 'API V1 Timelines List' do
       it 'returns http unprocessable entity' do
         get "/api/v1/timelines/list/#{list.id}", headers: headers
 
-        expect(response).to have_http_status(422)
-        expect(response.headers['Link']).to be_nil
+        expect(response)
+          .to have_http_status(422)
+          .and not_have_http_link_header
       end
     end
   end