fix: requires with task-level vars

[mokeko]

fix : #1768.

In Executor.compiledTask, a new ast.Task variable is created as the return value of the function. While most fields from origTask are carried over, the Vars field is not set. I have added a change to address this. Although the other fields are set using templater.Replace, it doesn't seem necessary for Vars. This is because e.Compiler.GetVariables at line 37 already calls templater.Replace internally.