[tests] Modified some tests to fit new classes

tests/testthat/test-export_utils.R

tests/testthat/test-generate_benchmark_script.R

tests/testthat/test-generate_class.R

tests/testthat/test-prj_time_loop.R

tests/testthat/test-read_in_prj.R

tests/testthat/test-read_in_utils.R

tests/testthat/test-scrape_benchmarks.R

tests/testthat/test-utils.R