ci: verify run-task and fetch-content still support Python 3.8

pyproject.toml

@@ -52,6 +52,7 @@ dev = [
   "sphinx-book-theme >=1.1.4",
   "sphinx-taskgraph>=0.1.0",
   "sphinxcontrib-mermaid>=1.0.0",
+  "vermin>=1.8.0",
   "zstandard>=0.25.0",
 ]
 

taskcluster/kinds/check/kind.yml

@@ -39,3 +39,15 @@ tasks:
         run:
             command: >-
                 uv run --all-extras pyright
+    scripts-min-python:
+        description: >-
+            Verify that the standalone scripts consumers run inside tasks
+            still support the oldest Python they're used with
+        treeherder:
+            symbol: check(scripts-min-python)
+        run:
+            command: >-
+                uv run vermin --target=3.8- --violations --eval-annotations --no-tips
+                src/taskgraph/run-task/run-task src/taskgraph/run-task/fetch-content &&
+                uv run --no-project --python 3.8 python src/taskgraph/run-task/run-task --help > /dev/null &&
+                uv run --no-project --python 3.8 python src/taskgraph/run-task/fetch-content --help > /dev/null

taskcluster/kinds/docker-image/kind.yml

@@ -27,7 +27,7 @@ tasks:
         symbol: I(py)
         parent: run-task
         args:
-            PYTHON_VERSIONS: "3.14t 3.14 3.13 3.12 3.11 3.10 3.9"
+            PYTHON_VERSIONS: "3.14t 3.14 3.13 3.12 3.11 3.10 3.9 3.8"
     run-task:
         symbol: I(rt)
         args: