tests: show how CSVs can include newlines

Sanity check for #145

spec/api/api_data_spec.rb

@@ -58,6 +58,15 @@ describe Squib::Deck do
         })
     end
 
+    it 'loads csv with newlines' do
+      hash = Squib.csv(file: csv_file('newline.csv'))
+      expect(hash).to eq({
+        'title' => ['Foo'],
+        'level' => [1],
+        'notes' => ["a\nb"]
+      })
+    end
+
   end
 
   context '#xlsx' do

spec/data/csv/newline.csv

@@ -0,0 +1,3 @@
+title,level,notes
+Foo,1,"a
+b"