[actions] update sandpaper workflow to version 0.16.12

Author: zkamvar

.github/workflows/README.md

@@ -43,7 +43,7 @@ This workflow does the following:
 #### Caching
 
 This workflow has two caches; one cache is for the lesson infrastructure and 
-the other is for the the lesson dependencies if the lesson contains rendered
+the other is for the lesson dependencies if the lesson contains rendered
 content. These caches are invalidated by new versions of the infrastructure and
 the `renv.lock` file, respectively. If there is a problem with the cache, 
 manual invaliation is necessary. You will need maintain access to the repository

.github/workflows/sandpaper-version.txt

@@ -1 +1 @@
-0.16.11
+0.16.12