Fix strategy validation

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 95.45455% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 97.12%. Comparing base (34107d7) to head (a3e068a). Report is 2 commits behind head on master.

Files	Patch %	Lines
model/strategies/properties.py	94.73%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #167 +/- ## ========================================== + Coverage 97.03% 97.12% +0.08% ========================================== Files 85 138 +53 Lines 2128 3648 +1520 ========================================== + Hits 2065 3543 +1478 - Misses 63 105 +42 ``` | [Flag](https://app.codecov.io/gh/diogomatoschaves/MyCryptoBot/pull/167/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Diogo+Matos+Chaves) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/diogomatoschaves/MyCryptoBot/pull/167/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Diogo+Matos+Chaves) | `97.12% <95.45%> (+0.08%)` | :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=Diogo+Matos+Chaves#carryforward-flags-in-the-pull-request-comment) to find out more.

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