Fixes related to MPL drawer

[MatteoRobbiati]

Thanks @sergiomtzlosa for the fixes already done in #1438. We can keep that PR to solve the coverage problems and use this one to fix asap the errors.

Checklist:

• [x] Reviewers confirm new code works as expected.
• [x] Tests are passing.
• [x] Coverage does not decrease (this is expected to decrease since we will fix it in #1438).
• [x] Documentation is updated.

[sergiomtzlosa]

great @MatteoRobbiati just let me know to get hands on

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.

Project coverage is 97.10%. Comparing base (7864590) to head (bf626f5). Report is 118 commits behind head on master.

Files with missing lines	Patch %	Lines
src/qibo/ui/mpldrawer.py	0.00%	9 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1444 +/- ## ========================================== - Coverage 99.94% 97.10% -2.84% ========================================== Files 78 81 +3 Lines 11324 11653 +329 ========================================== - Hits 11318 11316 -2 - Misses 6 337 +331 ``` | [Flag](https://app.codecov.io/gh/qiboteam/qibo/pull/1444/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/qibo/pull/1444/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=qiboteam) | `97.10% <0.00%> (-2.84%)` | :arrow_down: | 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.

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[renatomello]

@MatteoRobbiati I can't merge it since coverage is not passing. Idk if you have the right level of authorization for that or if it's just @scarrazza

[scarrazza]

Coverage is failing, correct?

[renatomello]

Coverage is failing, correct?

If I understood correctly, coverage fix is being implemented in #1438

[sergiomtzlosa]

Coverage is failing, correct?

If I understood correctly, coverage fix is being implemented in #1438

Yes, you are right

[MatteoRobbiati]

Yes, correct. With this we fix errors and with the other one we can fix coverage. If you prefer, we can fix everything there, but that will take a bit more time.

[renatomello]

Yes, correct. With this we fix errors and with the other one we can fix coverage. If you prefer, we can fix everything there, but that will take a bit more time.

I'd prefer if this is merged as is, so other PRs can move forward while #1438 fixes the coverage.

[scarrazza]

I agree, thanks.