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_test.go

@@ -130,3 +130,19 @@ jobs:
 	assert.Equal(t, workflow.Jobs["test"].Steps[3].Type(), StepTypeUsesDockerURL)
 	assert.Equal(t, workflow.Jobs["test"].Steps[4].Type(), StepTypeUsesActionLocal)
 }
+
+func TestStep_ShellCommand(t *testing.T) {
+	tests := []struct {
+		shell string
+		want  string
+	}{
+		{"pwsh", "pwsh -command . '{0}'"},
+		{"powershell", "powershell -command . '{0}'"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.shell, func(t *testing.T) {
+			got := (&Step{Shell: tt.shell}).ShellCommand()
+			assert.Equal(t, got, tt.want)
+		})
+	}
+}