Update run-test to python3.

Test: testrunner.py --host -t 001-Main
Change-Id: I1f95a57e88890c332f58303795ee93f4be7d575a
diff --git a/test/run-test b/test/run-test
index 0ebe241..f2e2a81 100755
--- a/test/run-test
+++ b/test/run-test
@@ -563,7 +563,7 @@
 # Cannot use readlink -m, as it does not exist on Mac.
 # Fallback to nuclear option:
 noncanonical_tmp_dir=$tmp_dir
-tmp_dir="`cd $oldwd ; python -c "import os; import sys; sys.stdout.write(os.path.realpath('$tmp_dir'))"`"
+tmp_dir="`cd $oldwd ; python3 -c "import os; import sys; sys.stdout.write(os.path.realpath('$tmp_dir'))"`"
 if [ -z $tmp_dir ] ; then
   err_echo "Failed to resolve $tmp_dir"
   exit 1