corrected an issue with set-alias on linux

src/pester-tests/Set-Alias.Tests.ps1

@@ -6,6 +6,7 @@
     }
 
     It "Should be able to have the same output between set-alias and the output of the function being aliased" {
+        set-alias -Name gd -Value Get-Date
         gd | Should Be $(Get-Date)
     }
 
@@ -20,4 +21,4 @@
 
         gd2 | Should Be $(gd)
     }
-}
+}