[PY] Cannot build gemini hello sample

[yesudeep]

See:

Uninstalled 1 package in 0.94ms
Installed 1 package in 1ms
2025-12-15 17:10:57 [debug    ] Creating a new global tracer provider for telemetry.
2025-12-15 17:10:57 [debug    ] local_telemetry_server exporter added succesfully.
Traceback (most recent call last):
  File "/Users/yesudeep/code/github.com/firebase/genkit/py/samples/google-genai-hello/src/google_genai_hello.py", line 51, in <module>
    from genkit.plugins.evaluators import (
  File "/Users/yesudeep/code/github.com/firebase/genkit/py/plugins/evaluators/src/genkit/plugins/evaluators/__init__.py", line 23, in <module>
    from genkit.plugins.evaluators.constant import (
  File "/Users/yesudeep/code/github.com/firebase/genkit/py/plugins/evaluators/src/genkit/plugins/evaluators/constant.py", line 27, in <module>
    from genkit.core.typing import ModelReference
ImportError: cannot import name 'ModelReference' from 'genkit.core.typing' (/Users/yesudeep/code/github.com/firebase/genkit/py/packages/genkit/src/genkit/core/typing.py)
/Users/yesudeep/.local/share/pnpm/global/5/.pnpm/@genkit-ai+tools-common@1.26.0_@types+node@22.13.5/node_modules/@genkit-ai/tools-common/lib/cjs/src/manager/process-manager.js:54
                    reject(new Error(`app process exited with code ${code}`));
                           ^

Error: app process exited with code 1
    at ChildProcess.<anonymous> (/Users/yesudeep/.local/share/pnpm/global/5/.pnpm/@genkit-ai+tools-common@1.26.0_@types+node@22.13.5/node_modules/@genkit-ai/tools-common/lib/cjs/src/manager/process-manager.js:54:28)
    at ChildProcess.emit (node:events:507:28)
    at ChildProcess._handle.onexit (node:internal/child_process:294:12)

Node.js v23.11.1

[yesudeep]

cc: @MengqinShen