Fix RSpec warning about false positives

Using `not_to raise_error` with a specific class can hide problems with
the code causing errors of another kind so follow the recommended
practice of not using a specific class.

Author: pixeltrix

spec/jobs/petition_signed_data_update_job_spec.rb

@@ -23,9 +23,7 @@ def running_the_job
     end
 
     it 'does not raise the deserialization problem (which would cause the worker to requeue the job)' do
-      expect {
-        running_the_job
-      }.not_to raise_error(ActiveJob::DeserializationError)
+      expect { running_the_job }.not_to raise_error
     end
   end