[llvm] [GitHub] Bump clang-tidy version to 21th and add sccache in CI (PR #160551)

[Aiden Grossman via llvm-commits]

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@@ -19,8 +19,6 @@ jobs:
     defaults:
       run:
         shell: bash
-    container:
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boomanaiden154 wrote:

Why are we dropping this? The default compiler in Github Actions is going to be much slower.

https://github.com/llvm/llvm-project/pull/160551