Bump pub to 3f0df78417f7c112b933fbcdc1c5c87bde680cb1

Changes:
```
> git log --format="%C(auto) %h %s" 4a0cd04..3f0df78
 https://dart.googlesource.com/pub.git/+/3f0df784 Close the global http client after `ensurePubspecResolved` (4199)
 https://dart.googlesource.com/pub.git/+/9532f0a8 Let add and remove act upon the work pubspec (4196)
 https://dart.googlesource.com/pub.git/+/2ce3da14 Remove stray lockfiles and packageconfigs from workspace (4194)
 https://dart.googlesource.com/pub.git/+/a44e2e51 Tests of workspace error handling (4195)
 https://dart.googlesource.com/pub.git/+/2179b765 Resolve workspace root and workPackage when invoking pub from any sub-directory (4186)
 https://dart.googlesource.com/pub.git/+/7a668d12 Update repository specification with info about the 'pub_display_url' field (4193)
 https://dart.googlesource.com/pub.git/+/cf9ba6c5 Use local pub in binstubs when testing (4192)
 https://dart.googlesource.com/pub.git/+/0b8a261e Import package:path `as p` everywhere (4187)
 https://dart.googlesource.com/pub.git/+/2a7c0e92 Update repository specification with info about the 'affected[].versions' fields in advisories (4191)

```

Diff: https://dart.googlesource.com/pub.git/+/4a0cd0403f70382feca9e17ae8854ffbef0fee98..3f0df78417f7c112b933fbcdc1c5c87bde680cb1/
Bug: #55289
Change-Id: Ifc2e6280cfbb83b463dd197b463d6841f0528e3e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/359480
Reviewed-by: Jonas Jensen <[email protected]>
Commit-Queue: Sigurd Meldgaard <[email protected]>

Author: sigurdm

DEPS

@@ -168,7 +168,7 @@ vars = {
   "path_rev": "a7b696071bd83d3ee0a0f1b57ac94d6b1f05cac4",
   "pool_rev": "c118f69d8a6441a8453bf7d455fd7c79d3ee1497",
   "protobuf_rev": "b7613581d847e1e36e76f0e36db3a412d8fea5b1",
-  "pub_rev": "4a0cd0403f70382feca9e17ae8854ffbef0fee98", # disable tools/rev_sdk_deps.dart
+  "pub_rev": "3f0df78417f7c112b933fbcdc1c5c87bde680cb1", # disable tools/rev_sdk_deps.dart
   "pub_semver_rev": "3175ba0a58a96fb23f8d68b5f5c44d1a5b30cc16",
   "shelf_rev": "1acbc673326e5b31280184744f2864a8f92c5b46",
   "source_map_stack_trace_rev": "c75649651d01826236e3ab7093d277a70756905a",