Bump http to f35d1e1467092f6a5edb2abf7071c4a99e8c737a

Changes:
```
> git log --format="%C(auto) %h %s" 778174b..f35d1e1
 https://dart.googlesource.com/http.git/+/f35d1e1 Require Dart 2.14, prepare to release v0.13.4 (#626)

```

Diff: https://dart.googlesource.com/http.git/+/778174bca2c13becd88ef3353309190b1e8b9479~..f35d1e1467092f6a5edb2abf7071c4a99e8c737a/
Change-Id: I302deb4e99d9c040e05473cd944b1eb64b619191
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/215243
Reviewed-by: Nate Bosch <nbosch@google.com>
Commit-Queue: Nate Bosch <nbosch@google.com>
Auto-Submit: Kevin Moore <kevmoo@google.com>

.dart_tool/package_config.json

@@ -11,7 +11,7 @@
     "constraint, update this by running tools/generate_package_config.dart."
   ],
   "configVersion": 2,
-  "generated": "2021-09-23T11:31:05.389095",
+  "generated": "2021-10-01T13:54:59.751334",
   "generator": "tools/generate_package_config.dart",
   "packages": [
     {
@@ -351,7 +351,7 @@
       "name": "http",
       "rootUri": "../third_party/pkg/http",
       "packageUri": "lib/",
-      "languageVersion": "2.12"
+      "languageVersion": "2.14"
     },
     {
       "name": "http_io",

DEPS

@@ -117,7 +117,7 @@ vars = {
   "http_io_rev": "2fa188caf7937e313026557713f7feffedd4978b",
   "http_multi_server_rev": "de1b312164c24a1690b46c6e97bd47eff40c4649",
   "http_parser_rev": "202391286ddc13c4c3c284ac5b511f04697250ed",
-  "http_rev": "778174bca2c13becd88ef3353309190b1e8b9479",
+  "http_rev": "f35d1e1467092f6a5edb2abf7071c4a99e8c737a",
   "icu_rev" : "81d656878ec611cb0b42d52c82e9dae93920d9ba",
   "intl_tag": "0.17.0-nullsafety",
   "jinja2_rev": "2222b31554f03e62600cd7e383376a7c187967a1",