Canonical CI: grouped-tests.yml + root test/test_groups.toml (#311)

Convert the root Tests.yml test workflow to the canonical thin caller of
SciML/.github/.github/workflows/grouped-tests.yml@v1, moving the
group x version x os matrix into a root test/test_groups.toml.

The matrix is reproduced exactly (27/27): groups Core, QA, NoPre, each
on versions ["1","lts","pre"] and OSes
["ubuntu-latest","macos-latest","windows-latest"]. runtests.jl already
dispatches on GROUP (Core/QA/NoPre), so no runtests.jl change is needed.
No with: inputs are required since the old caller used all defaults
(GROUP env var, check-bounds yes, coverage on, src,ext directories).

on: triggers and concurrency: are preserved verbatim; filename and
name: are unchanged to keep branch-protection status checks intact.

Co-authored-by: ChrisRackauckas-Claude <accounts@chrisrackauckas.com>
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: 3 people

.github/workflows/Tests.yml

@@ -18,25 +18,5 @@ concurrency:
 
 jobs:
   tests:
-    name: "Tests"
-    strategy:
-      fail-fast: false
-      matrix:
-        version:
-          - "1"
-          - "lts"
-          - "pre"
-        group:
-          - "Core"
-          - "QA"
-          - "NoPre"
-        os:
-          - "ubuntu-latest"
-          - "macos-latest"
-          - "windows-latest"
-    uses: "SciML/.github/.github/workflows/tests.yml@v1"
-    with:
-      julia-version: "${{ matrix.version }}"
-      group: "${{ matrix.group }}"
-      os: "${{ matrix.os }}"
+    uses: "SciML/.github/.github/workflows/grouped-tests.yml@v1"
     secrets: "inherit"

test/test_groups.toml

@@ -0,0 +1,11 @@
+[Core]
+versions = ["1", "lts", "pre"]
+os = ["ubuntu-latest", "macos-latest", "windows-latest"]
+
+[QA]
+versions = ["1", "lts", "pre"]
+os = ["ubuntu-latest", "macos-latest", "windows-latest"]
+
+[NoPre]
+versions = ["1", "lts", "pre"]
+os = ["ubuntu-latest", "macos-latest", "windows-latest"]