Pin CI Python to 3.13 to match Pipfile.lock (#179)

The PyTest workflow requests python-version: "3.x", which now resolves to
CPython 3.14. Pipfile.lock pins scipy==1.15.3, whose newest wheels are
cp313, so pip falls back to building scipy from its sdist. That build
needs OpenBLAS, which ubuntu-latest does not provide, and 'make setup-dev'
fails before any test runs.

Pinning to 3.13 is the newest interpreter the current lockfile resolves
against: scipy, numpy, pandas and shapely all publish cp313 manylinux
wheels, and the one sdist-only dependency (turfpy 0.0.7) is pure Python.

The publish workflow runs the same pipenv install against the same
lockfile, so it is pinned identically.

Author: caglarpir

.github/workflows/pypi-publish.yml

@@ -19,7 +19,9 @@ jobs:
       - name: Set up Python
         uses: actions/setup-python@v5
         with:
-          python-version: "3.x"
+          # Pinned rather than "3.x" for the same reason as pytest.yml: this
+          # job also runs `pipenv install --dev` against Pipfile.lock.
+          python-version: "3.13"
 
       - name: Install dependencies
         run: |

.github/workflows/pytest.yml

@@ -16,7 +16,10 @@ jobs:
     - name: Set up Python
       uses: actions/setup-python@v5
       with:
-        python-version: "3.x"
+        # Pinned rather than "3.x": Pipfile.lock pins scipy==1.15.3, which
+        # publishes wheels only up to cp313. On a newer interpreter pip falls
+        # back to the sdist, which needs OpenBLAS and fails on ubuntu-latest.
+        python-version: "3.13"
     - name: Install dependencies
       run: |
         make setup-dev