fix: use old auto-completion for 0.9.x compat

See toolshed/organising#644

Partial revert of 1f8662cd95

scripts/autocomplete/powershell

@@ -2,7 +2,7 @@ $fn = $($MyInvocation.MyCommand.Name)
 $name = $fn -replace "(.*)\.ps1$", '$1'
 Register-ArgumentCompleter -Native -CommandName $name -ScriptBlock {
      param($commandName, $wordToComplete, $cursorPosition)
-     $other = "$wordToComplete --generate-shell-completion"
+     $other = "$wordToComplete --generate-bash-completion"
          Invoke-Expression $other | ForEach-Object {
             [System.Management.Automation.CompletionResult]::new($_, $_, 'ParameterValue', $_)
          }