Update coverlet.msbuild to version 3.1.1

Author: 0xced

tests/Serilog.Formatting.Log4Net.Tests.csproj

@@ -7,7 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="coverlet.msbuild" Version="3.1.0" PrivateAssets="all" />
+    <PackageReference Include="coverlet.msbuild" Version="3.1.1" PrivateAssets="all" />
     <PackageReference Include="FluentAssertions" Version="6.3.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.0.0" />
     <PackageReference Include="PublicApiGenerator" Version="10.2.0" />