Removed the netcoreapp3.0 target from the library, as it is already covered by netstandard2.0

Source/QuestPDF/QuestPDF.csproj

@@ -19,7 +19,7 @@
         <Copyright>Marcin Ziąbek, QuestPDF contributors</Copyright>
         <PackageTags>PDF;C#;dotnet;csharp;.NET;PDF library;PDF document;PDF generation;PDF creation;PDF report;PDF invoice;PDF export;windows;linux;mac;azure;aws;open-source;open source;free;adobe;file;SVG;HTML;XPS</PackageTags>
         <Nullable>enable</Nullable>
-        <TargetFrameworks>netstandard2.0;netcoreapp3.0;net6.0;net8.0</TargetFrameworks>
+        <TargetFrameworks>netstandard2.0;net6.0;net8.0</TargetFrameworks>
         <IncludeSymbols>true</IncludeSymbols>
         <SymbolPackageFormat>snupkg</SymbolPackageFormat>
         <GenerateDocumentationFile>True</GenerateDocumentationFile>