Bump pub to 7745ee72d7089515cf0de04709504839609b896e

Changes:
```
> git log --format="%C(auto) %h %s" 30bfc43..7745ee7
 https://dart.googlesource.com/pub.git/+/7745ee72 Fix stray files check (4464)
 https://dart.googlesource.com/pub.git/+/b3b6b878 Forbid unknown description keys (after 3.7) (4458)

```

Diff: https://dart.googlesource.com/pub.git/+/30bfc439fedba1ee3daadcf542f1483479bc4909..7745ee72d7089515cf0de04709504839609b896e/
Change-Id: Ib9c105c3afd9683a34d245b20ff9bb5ec85b9965
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/399903
Reviewed-by: Sarah Zakarias <[email protected]>
Commit-Queue: Sigurd Meldgaard <[email protected]>

Author: sigurdm

DEPS

@@ -147,7 +147,7 @@ vars = {
   "package_config_rev": "76f2f6c245451da1fa24d7bbb00251b909e729a5",
   "pool_rev": "f85209d83cb0aa3c5612ed80de32df51ba580abd",
   "protobuf_rev": "da7279c56734cffed4deb1e3a6f93bdcefccf6b8",
-  "pub_rev": "30bfc439fedba1ee3daadcf542f1483479bc4909", # disable tools/rev_sdk_deps.dart
+  "pub_rev": "7745ee72d7089515cf0de04709504839609b896e", # disable tools/rev_sdk_deps.dart
   "pub_semver_rev": "8e9fcb9d3f89f06022387f906da4d380688f935c",
   "shelf_rev": "2b5b683e78f5cc84e479a43297fd7b5489d7db02",
   "source_maps_rev": "198d32bbde2f5736c04dfbab306a17096fd1648b",