Simplify prerelease version assertion to hyphen check (#21)

The prerelease version assertion in the test workflow was matching
against a hardcoded list of identifiers (`preview|rc|alpha|beta`),
making it brittle and incomplete.

## Changes

- **`.github/workflows/Action-Test.yml`**: Replace specific identifier
regex with a simple hyphen presence check — consistent with how
prerelease detection works elsewhere in `action.yml`

```diff
- if ($installed -notmatch '-(preview|rc|alpha|beta)\.') {
-     throw "Prerelease validation failed: installed version '$installed' does not contain a prerelease identifier (-preview, -rc, -alpha, -beta)."
+ if ($installed -notmatch '-') {
+     throw "Prerelease validation failed: installed version '$installed' does not contain a prerelease segment."
```

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: MariusStorhaug <17722253+MariusStorhaug@users.noreply.github.com>

Author: Copilot

.github/workflows/Action-Test.yml

@@ -101,11 +101,11 @@ jobs:
           }
 
           # For prerelease matrix entries, additionally assert the version string
-          # contains a prerelease identifier so we never silently fall back to stable.
+          # contains a prerelease segment so we never silently fall back to stable.
           $matrixVersion = '${{ matrix.version }}'
           if ($matrixVersion.Trim().ToLower() -eq 'prerelease') {
-              if ($installed -notmatch '-(preview|rc|alpha|beta)\.') {
-                  throw "Prerelease validation failed: installed version '$installed' does not contain a prerelease identifier (-preview, -rc, -alpha, -beta)."
+              if ($installed -notmatch '-') {
+                  throw "Prerelease validation failed: installed version '$installed' does not contain a prerelease segment."
               }
-              Write-Host "Prerelease check passed: '$installed' contains a prerelease identifier."
+              Write-Host "Prerelease check passed: '$installed' contains a prerelease segment."
           }