Bumb gh workflow actions/checkout from v2 to v3

Change-Id: I0f99ffe981a303b155cbf3cbbcdb29a92be81b69
diff --git a/.github/workflows/check-standard.yaml b/.github/workflows/check-standard.yaml
index b37a66d..5739ed3 100644
--- a/.github/workflows/check-standard.yaml
+++ b/.github/workflows/check-standard.yaml
@@ -29,7 +29,7 @@
       R_KEEP_PKG_SOURCE: yes
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
 
       - uses: r-lib/actions/setup-pandoc@v2