ci: add Trim test group to CI matrix

Runs the trim (JuliaC --trim=safe) compilation tests on Julia pre-release
(1.12+). Excludes lts and 1 since trim requires Julia 1.12+.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: asinghvi17

.github/workflows/CI.yml

@@ -60,10 +60,18 @@ jobs:
           - ImplicitDiscreteSolve
           - SimpleImplicitDiscreteSolve
 
+          - Trim
+
         version:
           - 'lts'
           - '1'
           - 'pre'
+        exclude:
+          # Trim tests require Julia 1.12+ (JuliaC / --trim=safe)
+          - group: Trim
+            version: 'lts'
+          - group: Trim
+            version: '1'
     steps:
       - uses: actions/checkout@v4
       - uses: julia-actions/setup-julia@v2