Use sf function st_layers instead of gdalUtils::ogrinfo

[damianooldoni]

Based on coding club experience, the chunk code in

tutorials/content/tutorials/spatial_standards_vector/index.Rmd

Lines 125 to 127 in 15139e7

	gdalUtils::ogrinfo("sac.gpkg") %>%
	cat(sep = "\n")
	```

should be replaced by the more intuitive function st_layers("sac.gpkg"), I think.
What do you think @florisvdh ?

[florisvdh]

Your suggestion is absolutely better and preferable @damianooldoni 👍 ! Thank you, coding club.