Bump GHA cache version

Author: csoneson

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

@@ -30,7 +30,7 @@ jobs:
       GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
       CURL_CONFIG: ${{ matrix.config.curlConfigPath }}curl-config
-      cache-version: v1
+      cache-version: v2
 
     steps:
       - name: Check out repo