[dagster-airlift] Dep-less setup.py (#26091)

## Summary & Motivation
Get rid of rich Airlift description within setup.py - make sure it's not
dependent on any other files which might not be downloaded as part of
the package for now.

python_modules/libraries/dagster-airlift/setup.py

@@ -46,9 +46,7 @@ def get_version() -> str:
     author="Dagster Labs",
     author_email="[email protected]",
     license="Apache-2.0",
-    description="Tooling to assist with migrating from Airflow to Dagster.",
-    long_description=Path("README.md").read_text(),
-    long_description_content_type="text/markdown",
+    description="A toolkit for observing integration and migration between Apache Airflow and Dagster.",
     url=(
         "https://github.com/dagster-io/dagster/tree/master/python_modules/libraries/"
         "dagster-airlift"