Fixing a "TypeError: sequence item 0: expected string, int found"

Bug introduced in Issue 407303003

BUG=
NOTRY=True

Review URL: https://codereview.chromium.org/417013002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@285394 0039d316-1c4b-4281-b951-d872f2087c98

tools/telemetry/telemetry/core/backends/chrome/android_browser_finder.py

@@ -250,7 +250,7 @@ Waiting for device...
           else:
             logging.warn(
                 'Cannot set CPU affinity due to stale psutil version: %s',
-                '.'.join(psutil.version_info))
+                '.'.join(str(x) for x in psutil.version_info))
       except (psutil.NoSuchProcess, psutil.AccessDenied):
         logging.warn('Failed to set adb process CPU affinity')