[llvm] ci: set minimal permission on github workflow (PR #69737)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-github-workflow

Author: Diogo Teles Sant'Anna (diogoteles08)

<details>
<summary>Changes</summary>

Relates to #<!-- -->69736

---
Full diff: https://github.com/llvm/llvm-project/pull/69737.diff


1 Files Affected:

- (modified) .github/workflows/libcxx-check-generated-files.yml (+3) 


``````````diff
diff --git a/.github/workflows/libcxx-check-generated-files.yml b/.github/workflows/libcxx-check-generated-files.yml
index 6f2d01ee0a56fdb..570055624b2a8d4 100644
--- a/.github/workflows/libcxx-check-generated-files.yml
+++ b/.github/workflows/libcxx-check-generated-files.yml
@@ -4,6 +4,9 @@ on:
     paths:
       - 'libcxx/**'
 
+permissions:
+  contents: read
+
 jobs:
   check_generated_files:
     runs-on: ubuntu-latest

``````````

</details>


https://github.com/llvm/llvm-project/pull/69737