fixed apt get error

Author: mr-cheffy

.github/workflows/ci.yaml

@@ -201,7 +201,7 @@ jobs:
             sudo add-apt-repository 'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-12 main' ||
             sudo add-apt-repository 'deb http://apt.llvm.org/focal/ llvm-toolchain-focal-12 main'
       - run: sudo apt-get update -y
-      - run: sudo apt-get install -y llvm-12 clang-12 lld-12
+      - run: sudo apt-get install -y llvm-12 clang-12 lld-12 --fix-missing
       - run: echo $(llvm-config-12 --bindir) >> $GITHUB_PATH
 
       # Setup: GCC