Roll gn from 468c6128db7f to c97a86a72105

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/gn-dart-sdk
Please CC dart-ecosystem-gardener@grotations.appspotmail.com,dart-engprod@google.com on the revert to ensure that a human
is aware of the problem.

To file a bug in gn: https://bugs.chromium.org/p/gn/issues/list
To file a bug in Dart SDK: https://github.com/dart-lang/sdk/issues

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

Cq-Include-Trybots: luci.dart.try:dart-sdk-linux-try;luci.dart.try:dart-sdk-mac-try;luci.dart.try:dart-sdk-mac-arm64-try;luci.dart.try:dart-sdk-win-try
Change-Id: Ib41119be9c247063cd68fcd31474593140c81555
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/402581
Reviewed-by: Alexander Aprelev <aam@google.com>
Reviewed-by: Siva Annamalai <asiva@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>

DEPS

@@ -79,7 +79,7 @@ vars = {
   "clang_version": "git_revision:388d7f144880dcd85ff31f06793304405a9f44b6",
 
   # https://chrome-infra-packages.appspot.com/p/gn/gn
-  "gn_version": "git_revision:468c6128db7fabe32a29d4753460ef53594406fc",
+  "gn_version": "git_revision:c97a86a72105f3328a540f5a5ab17d11989ab7dd",
 
   "reclient_version": "git_revision:c7349324c93c6e0d85bc1e00b5d7526771006ea0",
   "download_reclient": True,