chore: prep for v0.4.0 release

CHANGELOG.md

@@ -7,6 +7,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [0.4.0] - 2024-01-26
+
+### Removed
+
+* `pytket-quantinuum` dependency in https://github.com/CQCL/pytket-phir/pull/107
+  * **BREAKING**: Removes the `tket_optimization_level` argument to `pytket_to_phir`, i.e., input programs are expected to have any optimizations performed beforehand.
+
+### Fixed
+
+* A couple of bugs in parallel phirgen:
+  * Prevent parallel blocks in 1-qubit circuits in https://github.com/CQCL/pytket-phir/pull/109
+  * Stricter ordering checks in https://github.com/CQCL/pytket-phir/pull/112
+
 ## [0.3.0] - 2024-01-23
 
 ### Added
@@ -72,6 +85,7 @@ First release.
 [0.2.0]: https://github.com/CQCL/pytket-phir/compare/v0.1.2...v0.2.0
 [0.2.1]: https://github.com/CQCL/pytket-phir/compare/v0.2.0...v0.2.1
 [0.3.0]: https://github.com/CQCL/pytket-phir/compare/v0.2.1...v0.3.0
-[unreleased]: https://github.com/CQCL/pytket-phir/compare/v0.3.0...HEAD
+[0.4.0]: https://github.com/CQCL/pytket-phir/compare/v0.3.0...v0.4.0
+[unreleased]: https://github.com/CQCL/pytket-phir/compare/v0.4.0...HEAD
 
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