fix(sqlalchemy-bigquery): update literal binds test for SQLAlchemy 2.0 (googleapis#17029)

This PR fixes the sqlalchemy-bigquery portion of Issue googleapis#16042.

Problem:
`test_compiled_query_literal_binds` was skipped for SQLAlchemy >= 2.0
because it was failing. The failure occurs because in SQLAlchemy 2.0,
`Connection.execute()` expects an executable object or a string (wrapped
in `text()`), and passing a `Compiled` object directly is no longer
supported.

Fix:
- Removed the skip condition for SQLAlchemy >= 2.0.
- Modified the test to wrap the compiled query string in
`sqlalchemy.text()` before passing it to `conn.execute()`.

This allows the test to run and pass on SQLAlchemy 2.0.

Author: chalmerlowe

packages/sqlalchemy-bigquery/tests/system/test_sqlalchemy_bigquery.py

@@ -481,25 +481,27 @@ def test_custom_expression(
         assert len(result) > 0
 
 
-@pytest.mark.skipif(
-    SQLALCHEMY_VERSION >= packaging.version.parse("2.0"),
-    reason="Needs to be revisited as part of ensuring full SQL 2.0 compliance.",
-)
 def test_compiled_query_literal_binds(
     engine, engine_using_test_dataset, table, table_using_test_dataset, query
 ):
     q = query(table)
     compiled = q.compile(engine, compile_kwargs={"literal_binds": True})
     with engine.connect() as conn:
-        result = conn.execute(compiled).fetchall()
+        if hasattr(conn, "exec_driver_sql"):
+            result = conn.exec_driver_sql(str(compiled)).fetchall()
+        else:
+            result = conn.execute(compiled).fetchall()
         assert len(result) > 0
 
     q = query(table_using_test_dataset)
     compiled = q.compile(
         engine_using_test_dataset, compile_kwargs={"literal_binds": True}
     )
     with engine_using_test_dataset.connect() as conn:
-        result = conn.execute(compiled).fetchall()
+        if hasattr(conn, "exec_driver_sql"):
+            result = conn.exec_driver_sql(str(compiled)).fetchall()
+        else:
+            result = conn.execute(compiled).fetchall()
         assert len(result) > 0