Split JET tests into nopre group excluded from pre

- Update test/runtests.jl to use GROUP env pattern (Core and nopre groups)
- Update Tests.yml to run both groups, excluding nopre from prerelease Julia
- JET often has compatibility issues with prerelease Julia versions

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: claude

.github/workflows/Tests.yml

@@ -26,7 +26,14 @@ jobs:
           - "1"
           - "lts"
           - "pre"
+        group:
+          - Core
+          - nopre
+        exclude:
+          - version: "pre"
+            group: nopre
     uses: "SciML/.github/.github/workflows/tests.yml@v1"
     with:
       julia-version: "${{ matrix.version }}"
+      group: ${{ matrix.group }}
     secrets: "inherit"

test/runtests.jl

@@ -1,20 +1,27 @@
 using SafeTestsets
 
-@safetestset "Quality Assurance" begin
-    include("qa.jl")
-end
-@safetestset "Explicit Imports" begin
-    include("explicit_imports.jl")
-end
-@safetestset "JET Static Analysis" begin
-    include("jet.jl")
-end
-@safetestset "POD" begin
-    include("DataReduction.jl")
-end
-@safetestset "utils" begin
-    include("utils.jl")
+const GROUP = get(ENV, "GROUP", "All")
+
+if GROUP == "All" || GROUP == "Core"
+    @safetestset "Quality Assurance" begin
+        include("qa.jl")
+    end
+    @safetestset "Explicit Imports" begin
+        include("explicit_imports.jl")
+    end
+    @safetestset "POD" begin
+        include("DataReduction.jl")
+    end
+    @safetestset "utils" begin
+        include("utils.jl")
+    end
+    @safetestset "DEIM" begin
+        include("deim.jl")
+    end
 end
-@safetestset "DEIM" begin
-    include("deim.jl")
+
+if GROUP == "All" || GROUP == "nopre"
+    @safetestset "JET Static Analysis" begin
+        include("jet.jl")
+    end
 end