fix: PowerShell parse error — colon in string literal

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitea/workflows/build-release.yml

@@ -188,7 +188,7 @@ jobs:
             Write-Host "=== Update manifest uploaded ==="
           } else {
             Write-Host "WARNING: No .sig file found — update signing may have failed"
-            Write-Host "Sig files found:"
+            Write-Host "Sig files found"
             Get-ChildItem -Recurse src-tauri\target\release\bundle\nsis\*.sig
           }