Fix linting issue

Author: jasonbosco

spec/typesense_spec.rb

@@ -4,6 +4,6 @@
 
 describe Typesense do
   it 'has a version number' do
-    expect(Typesense::VERSION).not_to be_nil
+    expect(described_class::VERSION).not_to be_nil
   end
 end