🔥 Drop support for x86 macOS systems (#223)

## Description

As `tket` has dropped support for x86 macOS systems (see the [release
notes of v2.10.0](https://github.com/CQCL/tket/releases/tag/v2.10.0)),
we are following suit. `mqt-problemsolver` will no longer be tested on
such systems in the future.

## Checklist:

- [x] The pull request only contains commits that are focused and
relevant to this change.
- [x] ~I have added appropriate tests that cover the new/changed
functionality.~
- [x] ~I have updated the documentation to reflect these changes.~
- [x] The changes follow the project's style guidelines and introduce no
new warnings.
- [x] The changes are fully tested and pass the CI checks.
- [x] I have reviewed my own code changes.


<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Chores**
* Updated continuous integration matrix: swapped one macOS Intel runner
for a Windows ARM runner while keeping broad Ubuntu, macOS, and Windows
coverage to streamline CI maintenance without changing test scope or
public behavior.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Signed-off-by: Daniel Haag <[email protected]>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: denialhaag

.github/workflows/ci.yml

@@ -28,14 +28,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        runs-on:
-          [
-            ubuntu-24.04,
-            ubuntu-24.04-arm,
-            macos-15-intel,
-            macos-14,
-            windows-2022,
-          ]
+        runs-on: [ubuntu-24.04, ubuntu-24.04-arm, macos-14, windows-2022]
     uses: munich-quantum-toolkit/workflows/.github/workflows/reusable-python-tests.yml@56cf3608b07dc10bda5b98d77ed6ad21ecf7ef5d # v1.17.0
     with:
       runs-on: ${{ matrix.runs-on }}