Fix exception thrown by EF Core 8 preview

[bkoelman]

Fixes a bug where an unneeded SQL query was executed when updating a one-to-one relationship. This was silently ignored on earlier versions of Entity Framework Core, but fails in the preview version of v8. The fix is to only execute the query when needed.

Details at: dotnet/efcore#31271.

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• N/A: Adapted tests
• N/A: Documentation updated

[codecov]

Codecov Report

Merging #1289 (58b8f9f) into master (c0eb108) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 58b8f9f differs from pull request most recent head 336b725. Consider uploading reports for the commit 336b725 to get more accurate results

@@           Coverage Diff           @@
##           master    #1289   +/-   ##
=======================================
  Coverage   92.97%   92.97%           
=======================================
  Files         255      255           
  Lines        8254     8259    +5     
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+ Hits         7674     7679    +5     
  Misses        580      580           

Impacted Files	Coverage Δ
...ApiDotNetCore.SourceGenerators/SourceCodeWriter.cs	97.61% <100.00%> (ø)
...Core/Repositories/EntityFrameworkCoreRepository.cs	96.11% <100.00%> (+0.06%)	⬆️