Update CI

Author: savannahostrowski

.github/workflows/jit.yml

@@ -68,7 +68,7 @@ jobs:
           - true
           - false
         llvm:
-          - 20
+          - 21
         include:
           - target: i686-pc-windows-msvc/msvc
             architecture: Win32
@@ -138,7 +138,7 @@ jobs:
       fail-fast: false
       matrix:
         llvm:
-          - 20
+          - 21
     steps:
       - uses: actions/checkout@v4
         with:
@@ -193,7 +193,7 @@ jobs:
       fail-fast: false
       matrix:
         llvm:
-          - 20
+          - 21
     steps:
       - uses: actions/checkout@v4
         with: