Let PipeLine support copy()

[Vela-zz]

Let PipeLine support copy()

Description

now pipeline can be copied and add next-preprocessing step on needs withoud write duplicated append().

Fixes # (issue)

Type of Change

Please check any relevant options and delete the rest.

• New feature (non-breaking change which adds functionality)

How Has This Been Tested?

class TestPipeLine(unittest.TestCase):
    def test_copy(self):
        pipe = hanlp.pipeline().append(hanlp.utils.rules.split_sentence)
        copied_pipe = pipe.copy()
        test_text = "今天天气真好。我要去散步。"
        assert pipe is not copied_pipe
        copied_pipe.append(lambda sent: "".join(sent))
        assert pipe(test_text) != copied_pipe(test_text)

Checklist

Check all items that apply.

• ⚠️Changes must be made on dev branch instead of master
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have checked my code and corrected any misspellings

[hankcs]

Thank you!