adding shell definition in copy runs

[LAShemilt]

The template is causing errors in other repos G

GitHub.DistributedTask.ObjectTemplating.TemplateValidationException: The template is not valid. SciCatProject/docs-template/main/.github/actions/mkdocs-pages/action.yaml (Line: 41, Col: 7): Required property is missing: shell
   at GitHub.DistributedTask.ObjectTemplating.TemplateValidationErrors.Check()
   at GitHub.Runner.Worker.ActionManifestManager.ConvertRuns(IExecutionContext executionContext, TemplateContext templateContext, TemplateToken inputsToken, String fileRelativePath, MappingToken outputs)
   at GitHub.Runner.Worker.ActionManifestManager.Load(IExecutionContext executionContext, String manifestFile)

added shell definition to the copy command.

[minottic]

thanks! my bad...