Limit Pydantic < 2.0.0 until Airflow resolves incompatibilities (#1981)

Before this change, the project's `main` branch tests failed.

Example of error:
```
    module = import_module(module_path)
  File "/opt/hostedtoolcache/Python/3.8.17/x64/lib/python3.8/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1014, in _gcd_import
  File "<frozen importlib._bootstrap>", line 991, in _find_and_load
  File "<frozen importlib._bootstrap>", line 975, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 671, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 843, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/runner/work/astro-sdk/astro-sdk/python-sdk/.nox/test_examples_by_dependency-extras-sqlite-include-sqlite/lib/python3.8/site-packages/airflow/models/skipmixin.py", line 25, in <module>
    from airflow.serialization.pydantic.dag_run import DagRunPydantic
  File "/home/runner/work/astro-sdk/astro-sdk/python-sdk/.nox/test_examples_by_dependency-extras-sqlite-include-sqlite/lib/python3.8/site-packages/airflow/serialization/pydantic/dag_run.py", line 24, in <module>
    from airflow.serialization.pydantic.dataset import DatasetEventPydantic
  File "/home/runner/work/astro-sdk/astro-sdk/python-sdk/.nox/test_examples_by_dependency-extras-sqlite-include-sqlite/lib/python3.8/site-packages/airflow/serialization/pydantic/dataset.py", line 40, in <module>
    class TaskOutletDatasetReferencePydantic(BaseModelPydantic):
  File "/home/runner/work/astro-sdk/astro-sdk/python-sdk/.nox/test_examples_by_dependency-extras-sqlite-include-sqlite/lib/python3.8/site-packages/pydantic/_internal/_model_construction.py", line 95, in __new__
    private_attributes = inspect_namespace(
  File "/home/runner/work/astro-sdk/astro-sdk/python-sdk/.nox/test_examples_by_dependency-extras-sqlite-include-sqlite/lib/python3.8/site-packages/pydantic/_internal/_model_construction.py", line 328, in inspect_namespace
    raise PydanticUserError(
pydantic.errors.PydanticUserError: A non-annotated attribute was detected: `dag_id = <class 'str'>`. All model fields require a type annotation; if `dag_id` is not meant to be a field, you may be able to resolve this error by annotating it as a `ClassVar` or updating `model_config['ignored_types']`.
```
From:
https://github.com/astronomer/astro-sdk/actions/runs/5449375269/jobs/9913528880

Relates to: apache/airflow#32311

python-sdk/pyproject.toml

@@ -21,6 +21,7 @@ dependencies = [
  "attrs>=20.0",
  "pandas>=1.3.4,<2.0.0", # Pinning it to <2.0.0 to avoid breaking changes
  "pyarrow",
+ "pydantic>=1.10.0,<2.0.0", # Airflow & Pydantic issue: https://github.com/apache/airflow/issues/32311
  "python-frontmatter",
  "smart-open",
  "SQLAlchemy>=1.3.18",