[stable] Bump pub to 815d0777097de0c2dc6ce471699b594c9662dafe

Changes:
```
> git log --format="%C(auto) %h %s" 9d10254..815d077
 https://dart.googlesource.com/pub.git/+/815d0777 Properly handle case where the client is unable to fetch advisories  (4275)

```

Diff: https://dart.googlesource.com/pub.git/+/9d1025414395db2dac9d590d2e567c27064783d2..815d0777097de0c2dc6ce471699b594c9662dafe/
Change-Id: I02c0c49afd427931eaf19198a98477187af03ec6
Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/370882
Cherry-pick-request: TBA
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/370885
Reviewed-by: Jonas Jensen <jonasfj@google.com>

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 This is a patch release that:
 
+- Fixes an issue where pub would crash when failing to fetch advisories from
+ the server. (issue [pub#4269]).
+
 - Fixes an issue where `const bool.fromEnvironment('dart.library.ffi')` is true
   and conditional import condition `dart.library.ffi` is true in dart2wasm.
   (issue [#55948]).
@@ -9,8 +12,9 @@ This is a patch release that:
 - Fixes an issue where FFI calls with variadic arguments on MacOS Arm64
   would mangle the arguments. (issue [#55943]).
 
-[#55943]: https://github.com/dart-lang/sdk/issues/55943
+[pub#4269]: https://github.com/dart-lang/pub/issues/4269
 [#55948]: https://github.com/dart-lang/sdk/issues/55948
+[#55943]: https://github.com/dart-lang/sdk/issues/55943
 
 ## 3.4.3 - 2024-06-05
 

DEPS

@@ -169,7 +169,7 @@ vars = {
   "path_rev": "a7b696071bd83d3ee0a0f1b57ac94d6b1f05cac4",
   "pool_rev": "c118f69d8a6441a8453bf7d455fd7c79d3ee1497",
   "protobuf_rev": "b7613581d847e1e36e76f0e36db3a412d8fea5b1",
-  "pub_rev": "9d1025414395db2dac9d590d2e567c27064783d2", # disable tools/rev_sdk_deps.dart
+  "pub_rev": "815d0777097de0c2dc6ce471699b594c9662dafe", # disable tools/rev_sdk_deps.dart
   "pub_semver_rev": "3175ba0a58a96fb23f8d68b5f5c44d1a5b30cc16",
   "shelf_rev": "1acbc673326e5b31280184744f2864a8f92c5b46",
   "source_map_stack_trace_rev": "c75649651d01826236e3ab7093d277a70756905a",