T021/22: Deprecated tensorflow imports?

[dominiquesydow]

Description

Our scheduled CI shows fails for tensorflow imports on Windows. Compared to last week (passing CI), the installed tensorflow versions changed from 2.6 to 2.8.

ModuleNotFoundError: No module named 'tensorflow.python.keras.preprocessing'

Todos

• Look into possibly new import signatures as discussed here: ModuleNotFoundError: No module named 'tensorflow.python.keras.preprocessing' googlecolab/colabtools#2623
• The latest versions shown on conda-forge do not match the version installed during our CI. I do not know right now why. https://anaconda.org/conda-forge/tensorflow

[dominiquesydow]

I am confused by the following observation about the tensorflow versions that are installed in our CI runs. Leaving a summary here:

We ask for tensorflow>=2.0 (here) and specify the conda channels conda-forge and defaults (in that order!).
Let's check which tensorflow versions are installed vs. which I would expect (*) based on the latest conda-forge and defaults releases:

CI setup	observed CI version	expected CI version	conda-forge version	defaults version
Ubuntu Py3.8/3.9	2.4.1	2.9.1	2.9.1*	2.9.1
macOS Py3.8	2.4.1	2.9.1	2.9.1*	2.0.0
Windows Py3.9	2.8.2	2.8.2	1.14.0	2.8.2*
Windows Py3.8	2.3.0	2.8.2	1.14.0	2.8.2*

Maybe other dependencies in our teachopencadd environment prevent the installation of the lastest tensorflow versions?

Why do I care? It seems that there was an API change from tensorflow version 2.6.0 (last passing Win CI) to 2.8.2. Hence our T021 and T022 should get a refactoring based on the latest tensorflow version, no?
See deprecation note: https://www.tensorflow.org/api_docs/python/tf/keras/preprocessing

[dominiquesydow]

After consultation with @t-kimber, we concluded that our usage of tensorflow in T021 and T022 is basic enough to justify sticking to the API as of version 2.6. Hence, I am pinning tensorflow<=2.6, which should allow running the talktorials for all OS and Python 3.8 and 3.9.

Change is incorporated in PR #267, see #267 (comment).