scripts: update open calls to use explicit encoding

BUG=b:187789896
TEST=`cros lint` is clean here

Change-Id: Ia54475869c17292505537334362cd4cff6438b14
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/chromite/+/4290041
Commit-Queue: Cindy Lin <xcl@google.com>
Reviewed-by: Cindy Lin <xcl@google.com>
Tested-by: Mike Frysinger <vapier@chromium.org>
Auto-Submit: Mike Frysinger <vapier@chromium.org>
diff --git a/scripts/cros_sysroot_utils.py b/scripts/cros_sysroot_utils.py
index 2b4000a..b88d297 100644
--- a/scripts/cros_sysroot_utils.py
+++ b/scripts/cros_sysroot_utils.py
@@ -92,7 +92,7 @@
     # pylint: disable=consider-using-with
     output = sys.stdout
     if opts.out_file:
-        output = open(opts.out_file, "w")
+        output = open(opts.out_file, "w", encoding="utf-8")
 
     sysroot = sysroot_lib.Sysroot(opts.sysroot)
     if opts.command == "create-wrappers":