Currently uses tensorflow 2.4.3 due to Pyilastik

[pranjaldhole]

Currently we can only use tensorflow=2.4.3 which is automatically downgraded due to hard-fixed dependency in pyilastik that uses h5py==2.10.0 while tensorflow=2.6.0 requires at h5py=3.1.0.

Upgrading this requires updating PyIlastik with updating test data with versions consistent with the tests.

One attempt is here: yapic/pyilastik#8

[pranjaldhole]

We decided to discontinue support for pyilastik and ilastik-based labelling in favour of focussing development with newer annotation tools such as napari.

In the next commits the support of pyilastik will be removed including tests and test data.

[pranjaldhole]

yapic_io no longer has pyilastik as dependency. Commit yapic/yapic_io@c6f1a8c resolves #48