Fixes related to TF migration

[MatteoRobbiati]

A couple of modifications here are temporary and needed to make tests working both in Qibo and Qiboml.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 74.07%. Comparing base (7aa0eb9) to head (4d8722c). Report is 12 commits behind head on main.

Additional details and impacted files

[](https://app.codecov.io/gh/qiboteam/qiboml/pull/41?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) ```diff @@ Coverage Diff @@ ## main #41 +/- ## ========================================== + Coverage 73.88% 74.07% +0.19% ========================================== Files 5 5 Lines 134 135 +1 ========================================== + Hits 99 100 +1 Misses 35 35 ``` | [Flag](https://app.codecov.io/gh/qiboteam/qiboml/pull/41/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/qiboteam/qiboml/pull/41/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | `74.07% <100.00%> (+0.19%)` | :arrow_up: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files with missing lines](https://app.codecov.io/gh/qiboteam/qiboml/pull/41?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | Coverage Δ | | |---|---|---| | [src/qiboml/backends/\_\_init\_\_.py](https://app.codecov.io/gh/qiboteam/qiboml/pull/41?src=pr&el=tree&filepath=src%2Fqiboml%2Fbackends%2F__init__.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam#diff-c3JjL3FpYm9tbC9iYWNrZW5kcy9fX2luaXRfXy5weQ==) | `100.00% <100.00%> (ø)` | |