### Added
- ZAI env #1250
- Add ZAI component for reading headers #1256
- (PHP 8) Add proper exception and error reporting #1272
- (PHP 8) Register SpanData->exception property and store exception info there instead of internally #1281
### Changed
- Refactor internal span objects to be allocated together with their internal data #1254
- Enforce metrics to be floats in internal serializer #1258
- Allow for global debug mode, add zai testing to Makefile and more minor testing improvements #1265
- Move DDTrace\Format to src/api #1271
- Moving spans from userland to extension #1262
### Fixed
- Fix msgpack serialization of empty arrays #1259
- Set SECBIT_NO_SETUID_FIXUP to prevent crashes after setuid() calls #1276
- Apply original curl headers when curl_setopt_array() fails #1279
- Fix owner of files included in the distributed .tar.gz archive #1280
- Fix tests: Pin Symfony 4 tests to laminas/laminas-code < 4.4 #1266