ci: run the py3.12 tests in a non-UTC time zone

- a test that only passes in UTC now fails in CI

.github/workflows/ci.yml

@@ -11,12 +11,18 @@ concurrency:
 
 jobs:
   test:
-    name: tests (py${{ matrix.python-version }})
+    name: tests (py${{ matrix.python-version }}${{ matrix.tz && format(', {0}', matrix.tz) || '' }})
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
       matrix:
         python-version: ["3.10", "3.11", "3.12", "3.13"]
+        # One run away from UTC, so a test that only passes in UTC fails here.
+        include:
+          - python-version: "3.12"
+            tz: America/New_York
+    env:
+      TZ: ${{ matrix.tz }}
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-python@v5