fix: python3.9 support (#54)

Signed-off-by: Michele Dolfi <[email protected]>

.github/workflows/checks.yml

@@ -6,7 +6,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.10', '3.11', '3.12']
+        python-version: ['3.9', '3.10', '3.11', '3.12']
     steps:
       - uses: actions/checkout@v3
       - uses: ./.github/actions/setup-poetry

README.md

@@ -1,5 +1,5 @@
 [![PyPI version](https://img.shields.io/pypi/v/docling-ibm-models)](https://pypi.org/project/docling-ibm-models/)
-![Python](https://img.shields.io/badge/python-3.10%20|%203.11%20|%203.12-blue)
+[![PyPI - Python Version](https://img.shields.io/pypi/pyversions/docling-ibm-models)](https://pypi.org/project/docling-ibm-models/)
 [![Poetry](https://img.shields.io/endpoint?url=https://python-poetry.org/badge/v0.json)](https://python-poetry.org/)
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
 [![Imports: isort](https://img.shields.io/badge/%20imports-isort-%231674b1?style=flat&labelColor=ef8336)](https://pycqa.github.io/isort/)