📝 Prepare Release v3.1.0 (#658)

## Description

This PR prepares the CHANGELOG.md and the UPGRADING.md for the upcoming
release of v3.1.0 that includes the new NA compiler.

Additionally, it fixes a broken link that was overlooked in #624.

## Checklist:

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- [x] The pull request only contains commits that are focused and
relevant to this change.
- [ ] I have added appropriate tests that cover the new/changed
functionality.
- [ ] I have updated the documentation to reflect these changes.
- [x] I have added entries to the changelog for any noteworthy
additions, changes, fixes or removals.
- [x] I have added migration instructions to the upgrade guide (if
needed).
- [x] The changes follow the project's style guidelines and introduce no
new warnings.
- [ ] The changes are fully tested and pass the CI checks.
- [x] I have reviewed my own code changes.

Author: ystade

CHANGELOG.md

@@ -7,6 +7,8 @@ This project adheres to [Semantic Versioning], with the exception that minor rel
 
 ## [Unreleased]
 
+## [3.1.0] - 2025-05-26
+
 ### Added
 
 - ✨ Add new compilers for zoned neutral atom architectures (a routing-agnostic and routing-aware compiler) ([#624]) ([**@ystade**])
@@ -48,12 +50,14 @@ _📚 Refer to the [GitHub Release Notes] for previous changelogs._
 
 <!-- Version links -->
 
-[unreleased]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.0.0...HEAD
+[unreleased]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.1.0...HEAD
+[3.1.0]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.0.0...v3.1.0
 [3.0.0]: https://github.com/munich-quantum-toolkit/qmap/compare/v2.8.0...v3.0.0
 [2.8.0]: https://github.com/munich-quantum-toolkit/qmap/releases/tag/v2.8.0
 
 <!-- PR links -->
 
+[#624]: https://github.com/munich-quantum-toolkit/qmap/pulls/624
 [#621]: https://github.com/munich-quantum-toolkit/qmap/pulls/621
 [#614]: https://github.com/munich-quantum-toolkit/qmap/pulls/614
 [#610]: https://github.com/munich-quantum-toolkit/qmap/pulls/610

UPGRADING.md

@@ -4,6 +4,8 @@ This document describes breaking changes and how to upgrade. For a complete list
 
 ## [Unreleased]
 
+## [3.1.0]
+
 This minor release initiates the efforts to re-structure the Python bindings and make them more modular.
 Even tough this is not a breaking change, it is worth mentioning to developers of MQT QMAP that all Python code (except tests) has been moved to the top-level `python` directory.
 Furthermore, the C++ code for the Python bindings has been moved to the top-level `bindings` directory.
@@ -41,5 +43,6 @@ Most modern operating systems should have this version available in their packag
 Alternatively, CMake can be conveniently installed from PyPI using the [`cmake`](https://pypi.org/project/cmake/) package.
 
 [MQT SyReC]: https://github.com/cda-tum/mqt-syrec
-[unreleased]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.0.0...HEAD
+[unreleased]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.1.0...HEAD
+[3.1.0]: https://github.com/munich-quantum-toolkit/qmap/compare/v3.0.0...v3.1.0
 [3.0.0]: https://github.com/munich-quantum-toolkit/qmap/compare/v2.8.0...v3.0.0