Dict union operator replaced by traditional solution

[petrkaderabek]

Description

Dict union operator d1 | d2 was replaced by { **d1, **d2 }. The repo should be compatible with Python 3.8 but the dict union operator | is available in Python 3.9 and newer.

Incompatibility with Python 3.8 is unlucky, because the newest standard Tensorflow Docker images available from https://hub.docker.com/r/tensorflow/tensorflow/tags have Python version 3.8. The following error occurs:

TypeError: in user code:

    File "/usr/local/lib/python3.8/dist-packages/official/core/base_trainer.py", line 442, in eval_step  *
        return passthrough_logs | logs

    TypeError: unsupported operand type(s) for |: 'dict' and 'dict'

Type of change

• Bug fix (non-breaking change which fixes an issue)

Tests

I ran my code incl. the change and the previous error no longer occurs.

Test Configuration:
Docker image tensorflow/tensorflow:2.12.0-gpu-jupyter
Ubuntu 20.04
Nvidia 1080ti

Checklist

• I have signed the Contributor License Agreement.
• I have read guidelines for pull request.
• My code follows the coding guidelines.
• I have performed a self code review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have added tests that prove my fix is effective or that my feature works.

[laxmareddyp]

closing this PR as changes are pushed through internal CL.