Roll gn from 54169531ed6d to 97b68a0bb62b

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: I2a3f8026ba994c96427bed4b92f964c5c0619755
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/435563
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Alexander Aprelev <aam@google.com>
Reviewed-by: Alexander Aprelev <aam@google.com>

DEPS

@@ -78,7 +78,7 @@ vars = {
   "clang_version": "git_revision:8c7a2ce01a77c96028fe2c8566f65c45ad9408d3",
 
   # https://chrome-infra-packages.appspot.com/p/gn/gn
-  "gn_version": "git_revision:54169531ed6da64425ad6e8e9535945c8f6220d0",
+  "gn_version": "git_revision:97b68a0bb62b7528bc3491c7949d6804223c2b82",
 
   "reclient_version": "re_client_version:0.178.0.5ee9d3e8-gomaip",
   "download_reclient": True,