Update Tether JavaScript library version

Author: mdmintz

seleniumbase/fixtures/constants.py

@@ -117,7 +117,7 @@ class Shepherd:
 
 
 class Tether:
-    VER = "1.4.4"
+    VER = "1.4.7"
     MIN_JS = ("//cdnjs.cloudflare.com/ajax/libs/"
               "tether/%s/js/tether.min.js" % VER)