Adds devel pipeline that tests with unreleased direct dependencies

This should help us spot changes in other tools that would break
our extension before we release them.

.config/requirements-devel.in

@@ -0,0 +1 @@
+ansible-dev-environment @ git+https://github.com/ansible/ansible-dev-environment@main

.github/workflows/ci.yaml

@@ -77,6 +77,11 @@ jobs:
           - name: test (linux)
             task-name: test
 
+          - name: test-devel (linux)
+            task-name: test
+            env:
+              DEVEL: 1
+
           - name: test (macos)
             task-name: test
             os: macos-13-large

tools/test-setup.sh

@@ -294,8 +294,11 @@ if [[ $(uname || true) != MINGW* ]]; then # if we are not on pure Windows
     # We used the already tested constraints file from community-ansible-dev-tools EE in order
     # to avoid surprises. This ensures venv and community-ansible-dev-tools EE have exactly same
     # versions.
+    if [[ "${DEVEL:-}" == "1" ]]; then
+        PIP_DEVEL_ARGS=("-r" ".config/requirements-devel.in")
+    fi
     python3 -m uv pip install -q \
-        -r .config/requirements.in
+        -r .config/requirements.in "${PIP_DEVEL_ARGS[@]}"
 fi
 
 # GHA failsafe only: ensure ansible and ansible-lint cannot be found anywhere