Bump Microsoft.CodeAnalysis.CSharp from 4.0.1 to 5.0.0

---
updated-dependencies:
- dependency-name: Microsoft.CodeAnalysis.CSharp
  dependency-version: 5.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Ix.NET/Source/System.Linq.Async.SourceGenerator/System.Linq.Async.SourceGenerator.csproj

@@ -6,7 +6,7 @@
     <IsPackable>false</IsPackable>
   </PropertyGroup>
   <ItemGroup>
-    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="4.0.1" PrivateAssets="all" />
+    <PackageReference Include="Microsoft.CodeAnalysis.CSharp" Version="5.0.0" PrivateAssets="all" />
     <PackageReference Include="IsExternalInit" Version="1.0.3" PrivateAssets="all" />
   </ItemGroup>
 </Project>