Update pub revision

New in this update:
```
git log --oneline --no-decorate 9f00679ef47bc79cadc18e143720ade6c06c0100..980fc947db32bca6ae7d07fbb4ad0fcdba0050ec
980fc947 Add support for global activating package from a custom pub URL (#2041)
605cafb1 "features" is not a completely implemented or documented – hide flags (#2045)
73b66cd3 Merge pull request #2035 from sigurdm/logout_command
2b03587d dartfmt again
ea805dfb Fix help-expectation
6f759c1f gitfmt
90079421 deps: move package_resolver to a dev dependency
297f017a enable and fix a number of lints
f70ee39b Update to latest dependencies, require dart 2.1, fix lints
3446fb0d Add logout command
283471e7 Merge pull request #2016 from RedBrogdon/changelog
4c00f413 Update/add www.dartlang.org URLs (#2021)
f7b147f9 Correcting nerfed changelog test.
b9308223 Edited warning messages, addressed review issues.
9e9c8ed7 Fixed race conditions in test case. (#2020)
ec972168 Removed references to gitsubmodules (#2019)
ac8ad792 Copyright dates.
f9d35d34 Formatted via dartfmt.
a3351369 Adding ChangelogValidator to the list of validators.
a826b121 Adds changelog validator and its tests.
2233e3d5 Update the required pkg:http (#1996)
75d8453a Update all of the obvious dependencies
d07dafa5 Fix unnecessary `this` lints
43a91d12 Update to latest build_runner (#1966)
b3a2cfb7 Add check for a scheme on PUB_HOSTED_URL (#1972)
6626bda3 Update tests for SDK constraint validation (#1968)
```


Change-Id: Ib7c5ec86e5a6d67094b8e70a32ff41efe571c074
Reviewed-on: https://dart-review.googlesource.com/c/94380
Commit-Queue: Sigurd Meldgaard <sigurdm@google.com>
Reviewed-by: Jonas Jensen <jonasfj@google.com>

CHANGELOG.md

@@ -53,6 +53,13 @@ Upgraded the linter to `0.1.82` which adds the following improvements:
 *   Stopped registering "default lints".
 *   Fixed `hash_and_equals` to respect `hashCode` fields.
 
+#### Pub client
+
+* Added a CHANGELOG validator that complains if you `pub publish` without mentioning the current
+  version.
+* Added support for `pub global activate`ing package from a custom pub URL.
+* Added subcommand: `pub logout`. Logs you out of the current session.
+
 #### dart2js
 
 *  `--dump-info=binary`

DEPS

@@ -112,7 +112,7 @@ vars = {
   "ply_rev": "604b32590ffad5cbb82e4afef1d305512d06ae93",
   "pool_tag": "1.3.6",
   "protobuf_tag": "0.9.0",
-  "pub_rev": "9f00679ef47bc79cadc18e143720ade6c06c0100",
+  "pub_rev": "980fc947db32bca6ae7d07fbb4ad0fcdba0050ec",
   "pub_semver_tag": "1.4.2",
   "quiver_tag": "2.0.0+1",
   "resource_rev": "2.1.5",