Add support for US-TX (Texas) regional subdivision flag sequence

[TapForNerd]

This pull request adds support for the Texas state flag using the valid Unicode tag sequence:
🏴󠁵󠁳󠁴󠁸󠁿 (Black Flag + tags for U-S-T-X + Cancel Tag).

Motivation
As residents of San Antonio, Texas, we are deeply patriotic about our state and wish to enable representation of the Lone Star State's flag within Twemoji for users worldwide who value regional identity. The Texas flag is already supported on platforms such as WhatsApp (since late 2017) via this exact sequence, demonstrating practical demand.

Implementation Details

• Added SVG asset: assets/svg/1f3f4-e0075-e0073-e0074-e0078-e007f.svg
• Generated corresponding 72x72 PNG via the standard build process
• Updated version in package.json (incremented to 14.0.5)
• No core parser changes required, as Twemoji already handles valid tag sequences

Testing
The addition has been thoroughly tested across multiple browsers and devices:

• Chrome 143.0.7499.170 (Official Build, arm64) – Desktop
• Safari Version 26.2 (21623.1.14.11.9) – Desktop
• Chrome on Android
• Chrome on iOS
• Safari on iOS

Rendering works correctly when using { folder: 'svg', ext: '.svg' } or { folder: '72x72', ext: '.png' } with local assets/ base path.

Notes on Scope
We fully recognize that U.S. state flags (including US-TX) are classified as non-RGI by Unicode and are not recommended for general interchange. This addition is proposed as an optional enhancement for regional representation, similar to how certain platforms have independently supported this sequence. We are happy to discuss any adjustments or limitations the maintainers deem appropriate.

Thank you for considering this contribution. We appreciate the Twemoji project's role in making emoji accessible to everyone.

[CLAassistant]

All committers have signed the CLA.