Update MimeType.zep

[zikezhang]

Prevent fatal errors.

Hello!

• Type: bug fix
• Link to issue: [BUG]: MimeType:validate finfo error #16647

In raising this pull request, I confirm the following:

• I have read and understood the Contributing Guidelines
• I have checked that another pull request for this purpose does not exist
• I wrote some tests for this PR
• I have updated the relevant CHANGELOG
• I have created a PR for the documentation about this change

Small description of change:
Steps to Reproduce:

1. Form:

$this->add(
            (new File('file',['required' => true]))
                ->setLabel('Attach sample op-ed(available format:pdf,text,word):')
                ->addValidators([
                    new PresenceOf([
                        'message' => 'please upload an op-ed file',
                    ]),
                    new MimeType([
                        "types" => [
                            'application/pdf',
                            'application/msword',
                            'application/rtf',
                            'application/epub+zip',
                            'text/plain',
                        ],
                        "message" => "Allowed file types are :types"
                    ]),
                   new Max([
                        "size"     => "2M",
                        "included" => true,
                        "message"  => ":field exceeds the max size (:size)",
                    ])
                ])
        );
        
  Error: Fatal error: Uncaught ValueError: finfo_file(): Argument #1 ($finfo) cannot be empty in      

Thanks

[niden]

Thank you @zikezhang