golangci-lint: Fix file permission for gosec

If fixes following error
```
pkg/os/windows/powershell/powershell_windows.go:77:12: G306: Expect WriteFile permissions to be 0600 or less (gosec)
	if err := os.WriteFile(filename, append([]byte{0xef, 0xbb, 0xbf}, []byte(scriptContent)...), 0666); err != nil {
	          ^
```

pkg/os/windows/powershell/powershell_windows.go

@@ -74,7 +74,7 @@ func ExecuteAsAdmin(reason, cmd string) (string, string, error) {
 	filename := filepath.Join(tempDir, "runAsAdmin.ps1")
 
 	// #nosec G306
-	if err := os.WriteFile(filename, append([]byte{0xef, 0xbb, 0xbf}, []byte(scriptContent)...), 0666); err != nil {
+	if err := os.WriteFile(filename, append([]byte{0xef, 0xbb, 0xbf}, []byte(scriptContent)...), 0600); err != nil {
 		return "", "", err
 	}