Drop vestigial import of the tarfile module

The correlate() function stopped needing tarfile a couple of years
ago (version 2.4), but it was overlooked that the script continued
to unnecessarily import it. Clean this up.

weather.py

@@ -1227,7 +1227,7 @@ def gecos(formatted):
     return tuple(coordinates)
 
 def correlate():
-    import codecs, csv, datetime, hashlib, os, re, sys, tarfile, time, zipfile
+    import codecs, csv, datetime, hashlib, os, re, sys, time, zipfile
     if pyversion("3"): import configparser
     else: import ConfigParser as configparser
     for filename in os.listdir("."):