Encode arrays as json in requests

spec/telegram/bot/client_spec.rb

@@ -60,7 +60,7 @@ RSpec.describe Telegram::Bot::Client do
     subject { described_class.prepare_body(input) }
 
     context 'when plain hash is given' do
-      let(:input) { {a: 1, b: '2', c: [1, 2]} }
+      let(:input) { {a: 1, b: '2', c: nil} }
       it { should eq input }
     end
 
@@ -69,7 +69,7 @@ RSpec.describe Telegram::Bot::Client do
 
       it 'encodes nested hashes to json' do
         expected = input.dup
-        %i(d e).each { |x| expected[x] = expected[x].to_json }
+        %i(c d e).each { |x| expected[x] = expected[x].to_json }
         should eq expected
       end
     end