Fix CI script for Ubuntu

https://github.com/r-lib/actions/issues/559

Change-Id: I5cc1399141fd1cfea471e7bb1a864726c30fa1a4
diff --git a/.github/workflows/check-standard.yaml b/.github/workflows/check-standard.yaml
index 62c0f90..b37a66d 100644
--- a/.github/workflows/check-standard.yaml
+++ b/.github/workflows/check-standard.yaml
@@ -41,7 +41,7 @@
 
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
-          extra-packages: any::rcmdcheck
+          extra-packages: any::rcmdcheck, any::XML
           needs: check
 
       - uses: r-lib/actions/check-r-package@v2