Change ping server to avoid sl4a http ping error

Change the ping server from http to https to avoid the sl4a httpPing
error.

Test: Done
Bug:75288883

Change-Id: Ic7dd555b58ab3465de8997114d0c106206f66d9f
Signed-off-by: Qi Jiang <qijiang@google.com>
diff --git a/acts/framework/acts/test_utils/wifi/wifi_test_utils.py b/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
index 8e0b72c..4cba652 100755
--- a/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
+++ b/acts/framework/acts/test_utils/wifi/wifi_test_utils.py
@@ -39,7 +39,7 @@
 # Speed of light in m/s.
 SPEED_OF_LIGHT = 299792458
 
-DEFAULT_PING_ADDR = "http://www.google.com/robots.txt"
+DEFAULT_PING_ADDR = "https://www.google.com/robots.txt"
 
 
 class WifiEnums():