update llvm in ubuntu

Author: Ella-0

.github/workflows/blank.yml

@@ -35,8 +35,8 @@ jobs:
           wget https://apt.llvm.org/llvm.sh
           sed -e 's/samu/ninja/g' -i *.sh
           chmod +x llvm.sh
-          sudo ./llvm.sh 14
-          sudo apt install libclang-rt-14-dev llvm llvm-14
+          sudo ./llvm.sh 21
+          sudo apt install libclang-rt-21-dev llvm llvm-21
           /usr/bin/clang --version
           /usr/bin/llvm-ar --version
           /usr/bin/llvm-ranlib --version