Remove extra 'the'

Author: WardBrian

src/cmdstan/stansummary_helper.hpp

@@ -688,7 +688,7 @@ void write_sampler_info(const stan::io::stan_csv_metadata &metadata,
        << "For each parameter, ESS_bulk and ESS_tail measure the "
           "effective sample size "
           "for the entire sample (bulk) and for the "
-          "the .05 and .95 tails (tail), "
+          ".05 and .95 tails (tail), "
        << std::endl;
   *out << prefix
        << "and R_hat measures the potential scale reduction on split chains. "