[stable] Roll dart_style patch release to fix digit separators.

The 2.3.7 version of dart_style that shipped in Dart SDK 3.6.0
incorrectly parses Dart code at language version 3.3 instead of 3.6.
That means it doesn't handle number literals with digit separators. In
other words, `dart format` fails on any code that contains digit
separators.

This bumps the DEP to 2.3.8, which is a single-commit patch version from
2.3.7 that fixes the parser language version number. There are no other
dart_style changes in 2.3.8.

Bug: #59815
Change-Id: If2546edcd11bd424019d76b87c7c08695add331a
Cherry-pick: dart-lang/dart_style#1636
Cherry-pick-request: #59998
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/406204
Auto-Submit: Bob Nystrom <[email protected]>
Commit-Queue: Alexander Thomas <[email protected]>
Reviewed-by: Alexander Thomas <[email protected]>

Author: munificent

CHANGELOG.md

@@ -3,7 +3,13 @@
 - Fixes a bug where `HttpServer` responses were not correctly encoded
   if a "Content-Type" header was set (issue [#59719][]).
 
+- Fix `dart format` to parse code at language version 3.6 so that digit
+  separators can be parsed correctly (issue [#59815][], dart_style issue
+  [#1630][dart_style #1630]).
+
 [#59719]: https://github.com/dart-lang/sdk/issues/59719
+[#59815]: https://github.com/dart-lang/sdk/issues/59815
+[dart_style #1630]: https://github.com/dart-lang/dart_style/issues/1630
 
 ## 3.6.1 - 2025-01-08
 

DEPS

@@ -137,7 +137,7 @@ vars = {
   #   and land the review.
   #
   # For more details, see https://github.com/dart-lang/sdk/issues/30164.
-  "dart_style_rev": "5d35f4d829ffb8532d345d95d3e9504ae6cd839e", # disable tools/rev_sdk_deps.dart
+  "dart_style_rev": "71eb5a5ff85652b15f832259ca36826e23186488", # disable tools/rev_sdk_deps.dart
   "dartdoc_rev": "5df03dd913a0a2e20421cac61112aa84111160e0",
   "ecosystem_rev": "2d58550f9e3fd8ecbc3b2e4444095fcb204a66c6",
   "fixnum_rev": "83293b8ed86ccd574a94fcf4a2da43f31c1b43e0",