v1.0.0-rc4 Release

Note: this release picks up from extism/extism versions at the point where the php-sdk was extracted into its own repository. This way the progression of releases is correct on Packagist.

What's Changed

• ci: use new extism cli by @zshipko in #1
• chore: add website link to readme by @nilslice in #6
• feat: update the SDK to use the latest changes in the Extism runtime by @mhmd-azeez in #7

New Contributors

• @zshipko made their first contribution in #1
• @nilslice made their first contribution in #6
• @mhmd-azeez made their first contribution in #7

Full Changelog: https://github.com/extism/php-sdk/commits/v1.0.0-rc4