-nologo for powershell (fixes #452)

terminus-terminal/src/shells/powershellCore.ts

@@ -39,6 +39,7 @@ export class PowerShellCoreShellProvider extends ShellProvider {
             id: 'powershell-core',
             name: 'PowerShell Core',
             command: pwshPath,
+            args: ['-nologo'],
             env: {
                 TERM: 'cygwin',
             }

terminus-terminal/src/shells/windowsStock.ts

@@ -39,6 +39,7 @@ export class WindowsStockShellsProvider extends ShellProvider {
                 id: 'powershell',
                 name: 'PowerShell',
                 command: 'powershell.exe',
+                args: ['-nologo'],
                 env: {
                     TERM: 'cygwin',
                 }