Use pwsh instead of powershell

https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#defaultsrunshell

> This is the default shell used on Windows. The PowerShell Core. GitHub
  appends the extension .ps1 to your script name. If your self-hosted
  Windows runner does not have PowerShell Core installed, then
  PowerShell Desktop is used instead.

Fixes #1653

action.yml

@@ -58,7 +58,7 @@ runs:
         Set-StrictMode -Version Latest
         $action_path = $env:GITHUB_ACTION_PATH
         & bash --noprofile --norc "${action_path}/main.sh"
-      shell: powershell
+      shell: pwsh
       env:
         # NB: Sync with non-Windows case.
         INPUT_TOOL: ${{ inputs.tool }}