s3select:test_generate_projection wrong index of split

In s3select:test_generate_projection test, the response is split, but the wrong index is taken.
This fix can make the test pass:

orig: assert( abs(float(res.split("\n")[1]) - eval(e)) < epsilon )
fix: assert( abs(float(res.split("\n")[0]) - eval(e)) < epsilon )

Start with the s3select:test_generate_projection test and inspect the assertion that splits the response on "\n". Change the selected split index as described, then run the test and confirm that it passes.

Written by the indexing model from the issue text.