### Changed
- Make the legacy API a pure proxy to internal spans #1471
- Load the legacy tracer only when actually used #1449
- Update profiling to v0.4.0 #1495

### Added
- Add appsec library to the release bundle #1469
- Add appsec installation #1470

### Fixed
- Always emit NoopSpans if the tracer extension is disabled #1475
- fix dd_update_upstream_services on php5 #1476
- Setup: Error if profiling is given but unavailable #1477
- Ensure dropped spans are distinguishable from unfinished spans #1480
- Fix Span::setError docblock #1481
- Fix invalid reads in background sender #1483
- Restore support for manual distributed tracing #1484
- Remove version number from datadog-setup.php's help output #1487
- Improve error detection for datadog-setup.php #1489

### Internal changes
- Add parallelism to makefile for builds and test runs #1382
- Add profiling module to randomized tests #1412
- Run randomized internal API stress testing in CI #1445
- Switch to Symbols interface, cleanup tests #1465
- Improve Symbol Call interface, introduce closure support #1467
- Support in-tree builds of Tea #1472
- Sandbox Bailout #1473
- Patch zend_alloc.c to not crash in CI for PHP 7.0 to 7.2 #1478
- build tea once during development #1479
- Update PHP 8.1 dependencies, include laravel testing #1482
- Inline queue function pointers #1490
- Adjust stack sample max stack depth #1491
- Remove unused profiling components #1492