Add support for python 3.13

- Upgraded lxml to v5
- Added 3.13 to python matrix

Author: ciaranmccormick

.github/workflows/test.yml

@@ -11,6 +11,7 @@ jobs:
           - '3.10'
           - '3.11'
           - '3.12'
+          - '3.13'
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python ${{ matrix.python-version }}

pyproject.toml

@@ -27,7 +27,7 @@ classifiers = [
 dependencies = [
     "gtfs-realtime-bindings>=1.0.0,<2",
     "importlib-metadata>=4.0.0,<5",
-    "lxml>=4.7.1,<5",
+    "lxml>=4.7.1,<6",
     "protobuf>=3.20.0,<4",
     "pydantic>=2.8,<2.9",
     "python-dateutil>=2.8,<2.9",