Remove old working directory

This is required for hosted runners as the working directory is
retained.

.github/workflows/build.yaml

@@ -112,6 +112,7 @@ jobs:
             - name: Extract Matter SDK from tar
               working-directory: ./
               run: |
+                rm -rf project-chip
                 mkdir -p project-chip
                 cd project-chip
                 apt update && apt install zstd