fix: provide theme to SvgAssetLoader instead of SvgPicture

[Kirpal]

What does this change?

Since version 5.5.0+1, the SvgTheme no longer works. It doesn't work because flutter_svg has deprecated using the theme with the SvgPicture constructor, and suggests that you pass the theme to the bytes loader instead.

Fixes #531 🎯

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

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• Make sure to open a GitHub issue as a bug/feature request before writing your code! That way we can discuss the change, evaluate designs, and agree on the general idea
  • Ensure the tests (melos run test)
  • Ensure the analyzer and formatter pass (melos run format to automatically apply formatting)
• Appropriate docs were updated (if necessary)

[AlexV525]

Thanks for the update. But the changing files seem not being well-formatted.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.27%. Comparing base (dbc01db) to head (b427a82).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #532   +/-   ##
=======================================
  Coverage   97.27%   97.27%           
=======================================
  Files          22       22           
  Lines         772      772           
=======================================
  Hits          751      751           
  Misses         21       21           

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