support version in sgl-kernel (#3439)

sgl-kernel/developer_guide.md

@@ -52,4 +52,4 @@ The `sgl-kernel` is rapidly evolving. If you experience a compilation failure, t
 
 ### Release new version
 
-Update version in [pyproject.toml](https://github.com/sgl-project/sglang/blob/main/sgl-kernel/pyproject.toml) and [version.py](https://github.com/sgl-project/sglang/blob/main/sgl-kernel/version.py)
+Update version in [pyproject.toml](https://github.com/sgl-project/sglang/blob/main/sgl-kernel/pyproject.toml) and [version.py](https://github.com/sgl-project/sglang/blob/main/sgl-kernel/src/sgl-kernel/version.py)

sgl-kernel/src/sgl-kernel/__init__.py

@@ -36,6 +36,8 @@ from sgl_kernel.ops import (
     tree_speculative_sampling_target_only,
 )
 
+from .version import __version__
+
 __all__ = [
     "apply_rope_with_cos_sin_cache_inplace",
     "bmm_fp8",