refactor: Fix deprecations and fix return type of getCard()

[clussiana]

This PR fixes some deprecations triggered in php 8.4 (source)

The function getCard() can return null if no data is found. So I specified the return type and added a test.

There is still some deprecations on some attributes :

• Deprecated: Creation of dynamic property TCGdex\Model\Set::$abbreviation is deprecated
• Deprecated: Creation of dynamic property TCGdex\Model\Serie::$firstSet is deprecated
• Deprecated: Creation of dynamic property TCGdex\Model\Serie::$lastSet is deprecated

As they are more complex types, this is not included in this PR

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.85%. Comparing base (383f7ef) to head (44c5f7c).
Report is 24 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master      #94      +/-   ##
============================================
- Coverage     95.15%   92.85%   -2.30%     
- Complexity       90      103      +13     
============================================
  Files            10       13       +3     
  Lines           227      266      +39     
============================================
+ Hits            216      247      +31     
- Misses           11       19       +8     

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[Aviortheking]

Hi, thanks for the PR, I'll look at the others deprecations in #95