chore(core): fix RunnablePick method return types

[cbornet]

Following #31321, the Output type of RunnablePick is Any.

[codspeed-hq]

CodSpeed Performance Report

Merging #34208 will improve performances by 32.67%

_{Comparing cbornet:runnable-pick-any (9975f59) with master (1867521)¹}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

⚡ 13 improvements
⏩ 21 skipped²

Benchmarks breakdown

	Mode	Benchmark	BASE	HEAD	Change
⚡	WallTime	test_import_time[ChatPromptTemplate]	618.3 ms	518.8 ms	+19.18%
⚡	WallTime	test_import_time[PydanticOutputParser]	552.2 ms	466.3 ms	+18.43%
⚡	WallTime	test_import_time[CallbackManager]	481.3 ms	411.7 ms	+16.91%
⚡	WallTime	test_import_time[HumanMessage]	274.9 ms	237.1 ms	+15.94%
⚡	WallTime	test_async_callbacks_in_sync	24.5 ms	18.4 ms	+32.67%
⚡	WallTime	test_import_time[InMemoryRateLimiter]	178.8 ms	156.3 ms	+14.39%
⚡	WallTime	test_import_time[tool]	531.3 ms	452.7 ms	+17.35%
⚡	WallTime	test_import_time[RunnableLambda]	517.2 ms	433.9 ms	+19.21%
⚡	WallTime	test_import_time[Document]	192.3 ms	164.5 ms	+16.87%
⚡	WallTime	test_import_time[Runnable]	516.9 ms	440.5 ms	+17.33%
⚡	WallTime	test_import_time[LangChainTracer]	467 ms	387.6 ms	+20.51%
⚡	WallTime	test_import_time[InMemoryVectorStore]	656.4 ms	536.5 ms	+22.34%
⚡	WallTime	test_import_time[BaseChatModel]	544.7 ms	467.8 ms	+16.43%

Footnotes

1. No successful run was found on master (1ad9de4) during the generation of this report, so 1867521 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 21 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩