GHA: cache by runner architecture in addition to OS

Author: aitap

.github/workflows/R-CMD-check.yaml

@@ -58,8 +58,8 @@ jobs:
         uses: actions/cache@v4
         with:
           path: ${{ env.R_LIBS_USER }}
-          key: ${{ runner.os }}-${{ hashFiles('.github/R-version') }}-1-${{ hashFiles('.github/depends.Rds') }}
-          restore-keys: ${{ runner.os }}-${{ hashFiles('.github/R-version') }}-1-
+          key: ${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('.github/R-version') }}-1-${{ hashFiles('.github/depends.Rds') }}
+          restore-keys: ${{ runner.os }}-${{ runner.arch }}-${{ hashFiles('.github/R-version') }}-1-
 
       - name: Install system dependencies
         if: runner.os == 'Linux'