php modules: Add php81 support to php-uuid, php-zip, php-zstd

[stronk7]

Description

Just add support for php81 to the uuid, zip and zstd modules. I needed them so tried locally and they built without problem, so sharing.

Feel free to close this if you've some scheduled plan to incorporate all the missing php81 modules altogether.

Type(s)

• bugfix
• enhancement
• security fix

Tested on

macOS 11.5.2 20G95 x86_64
Xcode 12.5.1 12E507

Verification

Have you

• followed our Commit Message Guidelines?
• checked that there aren't other open pull requests for the same change?
• checked your Portfile with port lint?
• tried existing tests with sudo port test? (yes but there aren't test for the modules)
• tried a full install with sudo port -vst install?
• tested basic functionality of all binary files?

[macportsbot]

Notifying maintainers:
@ryandesign for port php-uuid, php-zip, php-zstd.

[ryandesign]

Third-party extensions don't get added until a PHP version reaches its first stable release, because sometimes there are changes before a stable release that cause e.g. the PHP extension directory name (i.e. the date embedded within it) to be changed, which would incur additional work in revising those third-party extensions again.