test: add codebase.create_pr tests

[christinewangcw]

No description provided.

[codecov]

❌ 1 Tests Failed:

Tests completed	Failed	Passed	Skipped
29	1	28	0

View the top 1 failed test(s) by shortest run time

::tests.unit.codegen.sdk.core.test_directory

Stack Traces | 0s run time

ImportError while importing test module '.../sdk/core/test_directory.py'.
Hint: make sure your test modules/packages have valid Python names.
Traceback:
.../sdk/core/test_directory.py:8: in <module>
    from codegen.sdk.codebase.codebase_graph import CodebaseGraph
E   ModuleNotFoundError: No module named 'codegen.sdk.codebase.codebase_graph'

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[github-actions]

🎉 This PR is included in version 0.9.0 🎉

The release is available on GitHub release

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