try RSPM in GH actions (take 4)

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

@@ -1,5 +1,6 @@
-# For help debugging build failures open an issue on the RStudio community with the 'github-actions' tag.
+## For help debugging build failures open an issue on the RStudio community with the 'github-actions' tag.
 # https://community.rstudio.com/new-topic?category=Package%20development&tags=github-actions
+## https://yamlchecker.com/
 on:
   push:
     branches:
@@ -47,7 +48,7 @@ jobs:
           extra-packages: any::rcmdcheck
           needs: check
           upgrade: 'TRUE'
-    - name: Install texlive etc.
+      - name: Install texlive etc.
         if: runner.os == 'Linux'
         run: sudo apt-get install texlive texlive-science texlive-latex-extra texlive-bibtex-extra