Include all sql_gen files in package (#4490)

When the bigquery-etl package is installed from pypi (or locally
via `pip install .`), the only non-py files included in the package
are those in the `package_data` section of setup.py.

Previously, with just those files, sql generation would fail due
to missing files. Because this directory is small, we should
include all files so no one accidentally runs into this problem
again.

Co-authored-by: Daniel Thorn <dthorn@mozilla.com>

setup.py

@@ -26,7 +26,7 @@ setup(
             "stripe/*.json",
             "stripe/*.yaml",
         ],
-        "sql_generators": ["*/templates/*"],
+        "sql_generators": ["**/*"],
     },
     include_package_data=True,
     install_requires=[