fix: add ninja as dependency for flashinfer v0.2

[zhyncs]

Motivation

Modifications

Checklist

• Format your code according to the Contributor Guide.
• Add unit tests as outlined in the Contributor Guide.
• Update documentation as needed, including docstrings or example tutorials.

[zhyncs]

batch_decode_with_kv_cache_dtype_q_bf16_dtype_kv_bf16_dtype_o_bf16_dtype_idx_i32_head_dim_128_posenc_0_use_swa_False_use_logits_cap_False should be supported without this workaround