update r action and cache

Author: chinandrew

.github/workflows/r_ci.yml

@@ -27,7 +27,7 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Set up R ${{ matrix.r-version }}
-        uses: r-lib/actions/setup-r@ffe45a39586f073cc2e9af79c4ba563b657dc6e3
+        uses: r-lib/actions/setup-r@v1
         with:
           r-version: ${{ matrix.r-version }}
       - name: Install libcurl
@@ -36,7 +36,7 @@ jobs:
         uses: actions/cache@v2
         with:
           path: ${{ env.R_LIBS_USER }}
-          key: ${{ runner.os }}-r-1-
+          key: ${{ runner.os }}-r-2-
       - name: Install dependencies
         run: |
           install.packages(c("remotes", "rcmdcheck"))