Split JET tests to separate test group excluded from Julia pre-release

- Add JET as a separate test group in CI matrix
- Exclude JET group from 'pre' Julia version (like OrdinaryDiffEq does)
- This prevents CI failures from upstream type inference changes in Julia RC

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

Author: claude

.github/workflows/CI.yml

@@ -22,10 +22,14 @@ jobs:
           - DataDrivenSR
           - DataDrivenSparse
           - DataDrivenLux
+          - JET
         version:
           - '1'
           - 'lts'
           - 'pre'
+        exclude:
+          - group: JET
+            version: 'pre'
     steps:
       - uses: actions/checkout@v6
       - uses: julia-actions/setup-julia@v2

test/runtests.jl

@@ -41,13 +41,11 @@ end
                 include("./commonsolve/commonsolve.jl")
             end
         end
-
-        # Run JET analysis tests only in CI or when GROUP explicitly includes JET
-        # Note: JET tests may take longer due to static analysis overhead
-        if get(ENV, "CI", "false") == "true" || get(ENV, "RUN_JET_TESTS", "false") == "true"
-            @safetestset "JET Static Analysis" begin
-                include("./jet_tests.jl")
-            end
+    elseif GROUP == "JET"
+        # JET tests are excluded from Julia pre-release versions in CI
+        # to avoid failures from upstream changes in type inference
+        @safetestset "JET Static Analysis" begin
+            include("./jet_tests.jl")
         end
     else
         dev_subpkg(GROUP)