GHA: Retry with 'Rmpi' as a dependency - take 4

Author: HenrikBengtsson

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

@@ -159,11 +159,11 @@ jobs:
 
       - name: Check MPI clusters (not macOS)
         if: runner.os != 'macOS'
-	env:
-	  NOT_CRAN=true
+        env:
+          NOT_CRAN=true
         run: |
-	  install.packages(c("Rmpi", "snow"))
-	  future:::testme("mpi")
+          install.packages(c("Rmpi", "snow"))
+          future:::testme("mpi")
 
       - name: Upload check results
         if: failure()