Unit testing for Python 3.10 does not work

[bstienen]

When testing the HDS package with Python 3.10, the following error pops up

Processing dependencies for high-dimensional-sampling==0.2.0
Searching for tensorflow
Reading https://pypi.org/simple/tensorflow/
No local packages or working download links found for tensorflow
error: Could not find suitable distribution for Requirement.parse('tensorflow')

I don't really understand where this error comes from, as there are no problems with Python 3.8 and 3.9. The tensorflow website even says that 3.10 is supported...