Address CR feedback: add error handling and fix newline

- Add check for missing installer manifest with error message
- Remove -NoNewline to preserve YAML file conventions

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: SteveSandersonMS

.github/workflows/winget.yml

@@ -44,8 +44,12 @@ jobs:
             --out manifests
           
           # Add PowerShell dependency to installer manifest
-          $installerManifest = Get-ChildItem -Path manifests -Filter "*.installer.yaml" -Recurse | Select-Object -First 1
-          $content = Get-Content $installerManifest -Raw
+          $installerManifest = Get-ChildItem -Path manifests -Filter "*.installer.yaml" -Recurse | Select-Object -First 1 -ExpandProperty FullName
+          if (-not $installerManifest) {
+            Write-Error "No installer manifest (*.installer.yaml) was found in the 'manifests' directory."
+            exit 1
+          }
+          $content = Get-Content -Path $installerManifest -Raw
           $dependency = @"
 Dependencies:
   PackageDependencies:
@@ -54,7 +58,7 @@ Dependencies:
 "@
           # Insert dependency block before the Installers section
           $content = $content -replace '(?m)^Installers:', "$dependency`nInstallers:"
-          Set-Content -Path $installerManifest -Value $content -NoNewline
+          Set-Content -Path $installerManifest -Value $content
 
           # Submit the modified manifest
           .\wingetcreate.exe submit manifests