🔧 Add symbols package per SourceLink guideline

Following latest guidelines: https://github.com/dotnet/sourcelink

- Add symbols package
- Don't include PDB in main nuget (smaller download size), remove `AllowedOutputExtensionsInPackageBuildOutputFolder`

Author: angularsen

UnitsNet.Serialization.JsonNet/UnitsNet.Serialization.JsonNet.csproj

@@ -27,11 +27,16 @@
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
 
-  <!-- SourceLink -->
+  <!-- SourceLink: https://github.com/dotnet/sourcelink -->
   <PropertyGroup>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
+
+    <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
-    <AllowedOutputExtensionsInPackageBuildOutputFolder>$(AllowedOutputExtensionsInPackageBuildOutputFolder);.pdb</AllowedOutputExtensionsInPackageBuildOutputFolder>
+
+    <!-- Optional: Build symbol package (.snupkg) to distribute the PDB containing Source Link -->
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
   </PropertyGroup>
 
   <!-- Strong name signing -->

UnitsNet/UnitsNet.csproj

@@ -27,11 +27,16 @@
     <TargetFramework>netstandard2.0</TargetFramework>
   </PropertyGroup>
 
-  <!-- SourceLink -->
+  <!-- SourceLink: https://github.com/dotnet/sourcelink -->
   <PropertyGroup>
     <PublishRepositoryUrl>true</PublishRepositoryUrl>
+
+    <!-- Optional: Embed source files that are not tracked by the source control manager in the PDB -->
     <EmbedUntrackedSources>true</EmbedUntrackedSources>
-    <AllowedOutputExtensionsInPackageBuildOutputFolder>$(AllowedOutputExtensionsInPackageBuildOutputFolder);.pdb</AllowedOutputExtensionsInPackageBuildOutputFolder>
+
+    <!-- Optional: Build symbol package (.snupkg) to distribute the PDB containing Source Link -->
+    <IncludeSymbols>true</IncludeSymbols>
+    <SymbolPackageFormat>snupkg</SymbolPackageFormat>
   </PropertyGroup>
 
   <!-- Strong name signing -->