Set up CompatHelper to check test and docs (#19)

Author: mtfishman

.github/workflows/CompatHelper.yml

@@ -75,7 +75,8 @@ jobs:
               push!(registries, Pkg.RegistrySpec(; url=registry_url, name=registry_name))
             end
           end
-          CompatHelper.main(; registries, bump_version=true)
+          subdirs = ["", "test", "docs"]
+          CompatHelper.main(; registries, subdirs, bump_version=true)
         shell: julia --color=yes {0}
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}