support/run-tests: reorder imports

Reorder imports using the isort utility to fix a warning from pylint3:

wrong-import-order: standard import "import multiprocessing" should be
placed before "import nose2"

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

support/testing/run-tests

@@ -1,9 +1,10 @@
 #!/usr/bin/env python3
 import argparse
-import sys
+import multiprocessing
 import os
+import sys
+
 import nose2
-import multiprocessing
 
 from infra.basetest import BRConfigTest