FIX: MacOS Pipelines CMake Installation (#214)

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[AB#38373](https://sqlclientdrivers.visualstudio.com/c6d89619-62de-46a0-8b46-70b92a84d85e/_workitems/edit/38373)

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### Summary   
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This pull request makes a small improvement to the CMake installation
step in the PR validation pipeline. The change ensures that any existing
installation of CMake is uninstalled before installing a fresh copy,
reducing the chance of tap conflicts during setup.

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Author: bewithgaurav

eng/pipelines/pr-validation-pipeline.yml

@@ -92,6 +92,9 @@ jobs:
 
   - script: |
       brew update
+      # Uninstall existing CMake to avoid tap conflicts
+      brew uninstall cmake --ignore-dependencies || echo "CMake not installed or already removed"
+      # Install CMake from homebrew/core
       brew install cmake
     displayName: 'Install CMake'