CSV export: format the test duration as float instead of rational, so that usual spreadsheet software can read it.
CSV export: format the test duration as float instead of rational, so that usual spreadsheet software can read it.

cl-test-grid/cl-test-grid,cl-test-grid/cl-test-grid,cl-test-grid/cl-test-grid,d35h/cl-test-grid,cl-test-grid/cl-test-grid,cl-test-grid/cl-test-grid,d35h/cl-test-grid