fix: update license field format in pyproject.toml for PyPI compatibility

- Change license from string to object format: {text = "Apache-2.0"}
- Add license classifiers for better PyPI metadata
- Fix InvalidDistribution error for license-expression and license-file fields

Author: xxsc0529

pyobsql-oceanbase-plugin/pyproject.toml

@@ -4,8 +4,16 @@ version = "0.1.0"
 description = "A python SDK for OceanBase SQL, including JSON Table support and SQLAlchemy dialect extensions."
 authors = [{name="shanhaikang.shk",email="shanhaikang.shk@oceanbase.com"}]
 readme = "README.md"
-license = "Apache-2.0"
+license = {text = "Apache-2.0"}
 keywords = ["oceanbase", "sql", "json-table", "sqlalchemy"]
+classifiers = [
+    "License :: OSI Approved :: Apache Software License",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.9",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+]
 requires-python = ">=3.9"
 
 dependencies = [