[PHPStan] Fix PHPStan notice on PHPStan 1.9.3

[samsonasik]

Description

Fix PHPStan notice on PHPStan 1.9.3:

Run vendor/bin/phpstan analyse
Note: Using configuration file /home/runner/work/CodeIgniter4/CodeIgniter4/phpstan.neon.dist.
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Error: Variable $cols in isset() always exists and is not nullable.
 ------ -------------------------------------------------------------- 
  Line   system/CLI/CLI.php                                            
 ------ -------------------------------------------------------------- 
  985    Variable $cols in isset() always exists and is not nullable.  

Ref https://github.com/codeigniter4/CodeIgniter4/actions/runs/3686745072/jobs/6239400007#step:11:15

Checklist:

• Securely signed commits

[samsonasik]

All green 🎉 , let's merge