Fix PDF Caption

[BenyFilho]

PR Details

This PR fixes the caption on PDF documents.

Description

This PR fixes the caption on PDF documents.

Related Issues

Closes #3789

How Has This Been Tested

// client initialization...

client.on('ready', async () => {
     const pdf = MessageMedia.fromFilePath('document.pdf');
     await client.sendMessage('xxxxxxxxxxx@c.us', pdf, { caption: 'Test Caption' });
});

You can try the fix by running one of the following commands:

• NPM
  npm install github:BenyFilho/whatsapp-web.js#fix_pdf_caption

• YARN
  yarn add github:BenyFilho/whatsapp-web.js#fix_pdf_caption

Types of changes

• Dependency change
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• I have updated the documentation accordingly (index.d.ts).
• I have updated the usage example accordingly (example.js)

[pawankray]

@BenyFilho
There is a problem with the filename on PDF documents