Remove pwsh -login and add Pwsh test (#660)

* Remove pwsh -login and add Pwsh test

* Add Shell Command Test for coverage

* 🧪 Move PWSH Platform definition to inline test, it can always be expanded out later

Reference: https://github.com/nektos/act/pull/660#discussion_r626171728

* Test MacOS Build for transient failure

Co-authored-by: mergify[bot] <37929162+mergify[bot]@users.noreply.github.com>

pkg/model/workflow.go

@@ -258,7 +258,7 @@ func (s *Step) ShellCommand() string {
 	case "", "bash":
 		shellCommand = "bash --login --noprofile --norc -e -o pipefail {0}"
 	case "pwsh":
-		shellCommand = "pwsh -login -command . '{0}'"
+		shellCommand = "pwsh -command . '{0}'"
 	case "python":
 		shellCommand = "python {0}"
 	case "sh":