chore: version bump Taskgraph v21.0.0

CHANGELOG.md

@@ -1,5 +1,24 @@
 # Change Log
 
+## [21.0.0] - 2026-04-13
+
+### Added
+
+- Ability for `run-task` to fetch arbitrary extra refs
+- Ability for Decision task to override params via Git notes
+
+### Fixed
+
+- Improved index route verification
+
+### Changed
+
+- BREAKING CHANGE: run-task and decision images now use Debian 13
+
+### Removed
+
+- BREAKING CHANGE: Removed docker-worker features: dind, privileged, loopback-audio
+
 ## [20.0.0] - 2026-03-17
 
 ### Added

docs/reference/migrations.rst

@@ -3,6 +3,15 @@ Migration Guide
 
 This page can help when migrating Taskgraph across major versions.
 
+20.x -> 21.x
+------------
+
+* If you have tasks using `docker-worker`'s `dind`, `privileged` or `loopback-audio`
+  features, they are no longer supported. Either avoid using these features or migrate
+  to a `generic-worker` pool with D2G payloads enabled.
+* Ensure any task's using the `run-task` or `decision` images work with the new
+  Debian 13 base.
+
 19.x -> 20.x
 ------------
 

pyproject.toml

@@ -1,7 +1,7 @@
 ### Project
 [project]
 name = "taskcluster-taskgraph"
-version = "20.0.0"
+version = "21.0.0"
 description = "Build taskcluster taskgraphs"
 readme = "README.rst"
 authors = [