Fix DownloadFunctionsTests/test_download_all_timeout

Individual downloads need individual destinations. I don't know why it
was working before. I'm not sure why it wasn't working now.

It's still broken, but for a different reason! :-)

csppfetch/test.py

@@ -404,7 +404,7 @@ class DownloadFunctionsTests(DTestCase):
     def test_download_all_timeout(self):
         with TemporaryDirectory() as dir:
             stats = csppfetch.DownloadStatistics()
-            url_to_dst = { f"http://geodb.ssec.wisc.edu/ancillary/2019_05_27_147/gfs.19052700_F{f:03d}.hdf" : dir+"/f" for f in range(3,22,3) }
+            url_to_dst = { f"http://geodb.ssec.wisc.edu/ancillary/2019_05_27_147/gfs.19052700_F{f:03d}.hdf" : dir+f"/f{f}" for f in range(3,22,3) }
 
             with self.assertRaises(csppfetch.timelimit.OutOfTime):
                 csppfetch.download_all(url_to_dst, stats, True, 1)