Revert "Remove code which has been superceded by Test::FailWarnings."

This reverts commit 00317d9524bd923923a9204dc3dcb7f80305e198.
Re-order use statements in t/01-detect.t.
Bumps version to 1.61.
v1.61

    - Reverts a commit that was causing a test to fail when a warning about
      File::Slurp was detected