CI: test clang 18 (#274)

Author: havogt

.github/workflows/CI.yml

@@ -14,7 +14,7 @@ jobs:
     container: ghcr.io/gridtools/gridtools-base:${{ matrix.compiler }}
     strategy:
       matrix:
-        compiler: [gcc-8, gcc-10, gcc-11, gcc-12, gcc-13, clang-10, clang-15, clang-16, clang-17]
+        compiler: [gcc-8, gcc-10, gcc-11, gcc-12, gcc-13, clang-10, clang-15, clang-16, clang-17, clang-18]
         build_type: [Debug, Release]
         exclude:
           - compiler: gcc-10
@@ -29,6 +29,8 @@ jobs:
             build_type: Debug
           - compiler: clang-15
             build_type: Debug
+          - compiler: clang-16
+            build_type: Debug
 
     steps:
       - uses: actions/checkout@v1