Bump dartdoc to e1295863b11c54680bf178ec9c2662a33b0e24be

Changes:
```
> git log --format="%C(auto) %h %s" c7f1160..e129586
 https://dart.googlesource.com/dartdoc.git/+/e1295863 Fix the check for the expected number of categorized libraries in Dart SDK (3962)
 https://dart.googlesource.com/dartdoc.git/+/591173b9 Fix enum links for exported enums (3957)
 https://dart.googlesource.com/dartdoc.git/+/c8dd09cb More cleanup from removal of SpecialClasses (3955)
 https://dart.googlesource.com/dartdoc.git/+/b082872d Bump the github-actions group with 3 updates (3954)
 https://dart.googlesource.com/dartdoc.git/+/30be5783 Bump dart_style to 3.0.0 (3950)
 https://dart.googlesource.com/dartdoc.git/+/65240335 Fix most comment reference issues (3946)
 https://dart.googlesource.com/dartdoc.git/+/51256a37 Avoid the PackageGraph.objectClass field. (3951)
 https://dart.googlesource.com/dartdoc.git/+/c8be8454 Combine two enums test classes into one. (3949)
 https://dart.googlesource.com/dartdoc.git/+/3d16206f Bump to version 8.3.1 (3944)
 https://dart.googlesource.com/dartdoc.git/+/e3ecb4d0 Append the href of each library with a slash (3940)
 https://dart.googlesource.com/dartdoc.git/+/7444b397 Bump the github-actions group with 2 updates (3938)
 https://dart.googlesource.com/dartdoc.git/+/ced0209e Split existing CSS styles into multiple scss partials (3920)

```

Diff: https://dart.googlesource.com/dartdoc.git/+/c7f11603effa88ddacabfd555993f322fca8b3fe..e1295863b11c54680bf178ec9c2662a33b0e24be/
Change-Id: I1b30aec2bb4aca4dff781f84fa45df91e6ca9904
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/403941
Commit-Queue: Devon Carew <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>

DEPS

@@ -131,7 +131,7 @@ vars = {
   # EOL comment after a dependency to disable this and pin it at its current
   # revision.
   "core_rev": "7a71ad6b9170e09d5cbe39f3fccdee648659f1e7",
-  "dartdoc_rev": "c7f11603effa88ddacabfd555993f322fca8b3fe",
+  "dartdoc_rev": "e1295863b11c54680bf178ec9c2662a33b0e24be",
   "ecosystem_rev": "efe4ee4af6ac2e4c90aa525fae213b65c97295a9",
   "flute_rev": "e4ea0459a7debae5e9592c85141707b01fac86c9",
   "glob_rev": "eee18d1a577d5f965f6afbbd251798e065dced43",