ci: add Python 3.14 to test matrix

MIPster wheels are py3-none-* (Python-version agnostic) so no solver
changes are needed. cffi 2.0.0 works on 3.14.

- Add 3.14 to CI matrix
- Set allow-prereleases: true (future-proof for new releases)
- Add Python 3.14 classifier to pyproject.toml

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: h-g-s

.github/workflows/github-ci.yml

@@ -43,7 +43,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.10", "3.11", "3.12", "3.13", "pypy3.11"]
+        python-version: ["3.10", "3.11", "3.12", "3.13", "3.14", "pypy3.11"]
         os: [macos-15, ubuntu-24.04, ubuntu-24.04-arm, windows-2025]
         exclude:
           - python-version: "pypy3.11"
@@ -57,7 +57,7 @@ jobs:
       uses: actions/setup-python@v5
       with:
         python-version: ${{ matrix.python-version }}
-        allow-prereleases: false
+        allow-prereleases: true
 
     - name: Cache pip dependencies
       uses: actions/cache@v4

pyproject.toml

@@ -28,6 +28,7 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
     "Programming Language :: Python :: 3.12",
     "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Programming Language :: Python :: Implementation :: CPython",
     "Programming Language :: Python :: Implementation :: PyPy",
     "Topic :: Scientific/Engineering :: Mathematics"