add suggestion to use cache action if no depot is detected (#41)

action.yml

@@ -21,6 +21,9 @@ inputs:
     description: 'Determine if Pkg uses the cli git executable (Julia >= 1.7). Might be necessary for more complicated SSH setups.
                   Options: true | false. Default : false'
     default: 'false'
+  ignore-no-cache:
+    description: 'Whether to ignore if there appears to be no depot caching. Silences an action notice recommending `julia-actions/cache`.'
+    default: 'false'
 
 runs:
   using: 'composite'
@@ -29,8 +32,11 @@ runs:
     run: echo "JULIA_PKG_SERVER_REGISTRY_PREFERENCE=${JULIA_PKG_SERVER_REGISTRY_PREFERENCE:-eager}" >> ${GITHUB_ENV}
     shell: bash
   - run: |
+      if "${{ inputs.ignore-no-cache }}" == "false" && !isdir(DEPOT_PATH[1])
+          println("::notice title=[julia-buildpkg] Caching of the julia depot was not detected ::Consider using `julia-actions/cache` to speed up runs https://github.com/julia-actions/cache. To ignore, set input `ignore-no-cache: true` ")
+      end
       import Pkg
-      
+
       # Determine if Pkg uses git-cli executable instead of LibGit2
       VERSION >= v"1.7-" && (ENV["JULIA_PKG_USE_CLI_GIT"] = ${{ inputs.git_cli }})
 
@@ -44,14 +50,14 @@ runs:
 
           # If provided add local registries
           if !isempty("${{ inputs.localregistry }}")
-            local_repos = split("${{ inputs.localregistry }}", "\n") .|> string   
+            local_repos = split("${{ inputs.localregistry }}", "\n") .|> string
             for repo_url in local_repos
               isempty(repo_url) && continue
               Pkg.Registry.add(Pkg.RegistrySpec(; url = repo_url))
             end
           end
       end
-      
+
       VERSION >= v"1.1.0-rc1" ? retry(Pkg.build)(verbose=true) : retry(Pkg.build)()
     shell: julia --color=yes --project=${{ inputs.project }} {0}
     env: