Fix tests

[codecov[bot]]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.04% :warning:

Comparison is base (84baede) 92.72% compared to head (921449b) 92.69%. Report is 1 commits behind head on dev.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## dev #14 +/- ## ========================================== - Coverage 92.72% 92.69% -0.04% ========================================== Files 6 6 Lines 440 438 -2 ========================================== - Hits 408 406 -2 Misses 32 32 ``` | Flag | Coverage Δ | | |---|---|---| | unittests | `92.69% <100.00%> (-0.04%)` | :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=biosimulators#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files Changed](https://app.codecov.io/gh/biosimulators/Biosimulators_tellurium/pull/14?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biosimulators) | Coverage Δ | | |---|---|---| | [biosimulators\_tellurium/\_version.py](https://app.codecov.io/gh/biosimulators/Biosimulators_tellurium/pull/14?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biosimulators#diff-Ymlvc2ltdWxhdG9yc190ZWxsdXJpdW0vX3ZlcnNpb24ucHk=) | `100.00% <100.00%> (ø)` | | | [biosimulators\_tellurium/core.py](https://app.codecov.io/gh/biosimulators/Biosimulators_tellurium/pull/14?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biosimulators#diff-Ymlvc2ltdWxhdG9yc190ZWxsdXJpdW0vY29yZS5weQ==) | `91.62% <100.00%> (-0.05%)` | :arrow_down: |

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