fix: accidental removal of decorator and handle blank string for regular price

[dvdl16]

Description

• fix: accidental removal of decorator
• fix: handle blank string for regular price

Type of change

• 🟢 Bug fix (change which fixes an issue)
• ⚪ New feature (change which adds functionality)
• ⚪ Breaking change (fix or feature that would cause existing functionality to not work as expected)

Tests

• [ ] Unit Tests have been updated or added, as required
• [ ] UI Tests have been updated or added, as required

Checklist:

• [x] My code follows Naming Guidelines (DocType, Field and Variable naming)
• [x] No Form changes / My code follows the Form Design Guidelines
• [x] My code follows the Coding Standards of this project
• [x] My code follows the Code Security Guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas / No comments necessary
• [x] I have made corresponding additions/changes to the documentation
• [x] All business logic and validations are on the server-side / No business logic or validation changes
• [x] No patches are necessary / Migration Patches have been added to the correct subdirectory of /patches and patches.txt have been updated

User Experience:

N/A

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.38%. Comparing base (33a2eee) to head (ee6c057). Report is 1 commits behind head on version-15.

Files	Patch %	Lines
woocommerce_fusion/__init__.py	0.00%	1 Missing :warning:
woocommerce_fusion/tasks/sync_item_prices.py	50.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## version-15 #87 +/- ## ============================================== - Coverage 78.41% 78.38% -0.03% ============================================== Files 23 23 Lines 1251 1254 +3 ============================================== + Hits 981 983 +2 - Misses 270 271 +1 ```

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