Activate venv in nixlbench container

[ovidiusm]

What?

Activate virtual environment explicitly in nixlbench container

Why?

Python3 should work out of the box when a shell is opened.

Test

$ docker images
REPOSITORY                                                           TAG                                                                                    IMAGE ID       CREATED          SIZE
nixlbench                                                            v0.6.0.dev.bc2c2c19                                                                    755bf7ea398d   23 minutes ago   28GB

$ docker run -it 755bf7ea398d python3
                                                                                                                                                                                                                                                                                                                                                                                          ==========
== CUDA ==
==========

NVIDIA Release  (build )
CUDA Version 12.9.1.010
Container image Copyright (c) 2025, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
                                                                                                                                                                                                                                                                                                                                                                                          Various files include modifications (c) NVIDIA CORPORATION & AFFILIATES.  All rights reserved.

GOVERNING TERMS: The software and materials are governed by the NVIDIA Software License Agreement
(found at https://www.nvidia.com/en-us/agreements/enterprise-software/nvidia-software-license-agreement/)
and the Product-Specific Terms for NVIDIA AI Products
(found at https://www.nvidia.com/en-us/agreements/enterprise-software/product-specific-terms-for-ai-products/).
                                                                                                                                                                                                                                                                                                                                                                                          WARNING: The NVIDIA Driver was not detected.  GPU functionality will not be available.
   Use the NVIDIA Container Toolkit to start this container with GPU support; see
   https://docs.nvidia.com/datacenter/cloud-native/ .
                                                                                                                                                                                                                                                                                                                                                                                          NOTE: The SHMEM allocation limit is set to the default of 64MB.  This may be
   insufficient for CUDA.  NVIDIA recommends the use of the following flags:
   docker run --gpus all --ipc=host --ulimit memlock=-1 --ulimit stack=67108864 ...

Python 3.12.3 (main, Aug 14 2025, 17:47:21) [GCC 13.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

[github-actions]

👋 Hi ovidiusm! Thank you for contributing to ai-dynamo/nixl.

Your PR reviewers will review your contribution then trigger the CI to test your changes.

🚀

[ovidiusm]

/build

[ovidiusm]

/build