fix: Always verify via subprocess on Windows and prepend install dir to GITHUB_PATH

After MSI install on Windows, the running shell may still resolve the
pre-installed pwsh from PATH. Two fixes:

1. action.yml: Append the install directory to GITHUB_PATH so that
   subsequent 'shell: pwsh' steps in the consumer's workflow resolve to
   the version we just installed (critical for preview builds whose
   7-preview dir is not on the runner's default PATH, but also defensive
   for stable upgrades).

2. Action-Test.yml: Verification step now always launches pwsh from the
   known install directory on Windows (both stable and prerelease),
   instead of relying on $PSVersionTable from the current shell.

Author: MariusStorhaug

.github/workflows/Action-Test.yml

@@ -71,16 +71,19 @@ jobs:
               Write-Host "Resolved 'latest' → $requested"
           }
 
-          # For prerelease versions on Windows, launch the installed pwsh to get the version
-          # because the current shell may not be the version we just installed.
-          $isPrerelease = $requested -match '-'
-          if ($IsWindows -and $isPrerelease) {
+          # On Windows, always verify by launching pwsh from the known install directory.
+          # This avoids relying on PATH resolution, which may still point to the pre-installed
+          # version if the runner's environment hasn't refreshed after the MSI install.
+          if ($IsWindows) {
+              $isPrerelease = $requested -match '-'
               $majorVersion = ($requested -split '[\.-]')[0]
-              $installDir = "$majorVersion-preview"
+              $installDir = if ($isPrerelease) { "$majorVersion-preview" } else { $majorVersion }
               $pwshPath = "$env:ProgramFiles\PowerShell\$installDir\pwsh.exe"
+              Write-Host "Windows: verifying via subprocess at $pwshPath"
               if (Test-Path $pwshPath) {
                   $installed = (& $pwshPath -NoLogo -NoProfile -Command '$PSVersionTable.PSVersion.ToString()')
               } else {
+                  Write-Host "Warning: Expected pwsh not found at $pwshPath, falling back to `$PSVersionTable"
                   $installed = ($PSVersionTable.PSVersion).ToString()
               }
           } else {

action.yml

@@ -332,3 +332,19 @@ runs:
         }
 
         Write-Host "Installation complete. PowerShell [$($env:REQUESTED_VERSION)] is now available."
+
+        # Add the install directory to GITHUB_PATH so subsequent `shell: pwsh` steps
+        # resolve to the version we just installed — even for preview builds whose
+        # install directory (7-preview) is not on the runner's default PATH.
+        $isPrerelease = $env:REQUESTED_VERSION -match '-'
+        $installDir = if ($isPrerelease) {
+            "$env:ProgramFiles\PowerShell\7-preview"
+        } else {
+            "$env:ProgramFiles\PowerShell\7"
+        }
+        if (Test-Path $installDir) {
+            Write-Host "Adding install directory to GITHUB_PATH: $installDir"
+            Add-Content -Path $env:GITHUB_PATH -Value $installDir
+        } else {
+            Write-Host "Warning: Expected install directory not found: $installDir"
+        }