Bump coverlet.msbuild from 2.8.0 to 2.8.1 (#66)

Author: dependabot-preview[bot]

WebDriverManager.Tests/WebDriverManager.Tests.csproj

@@ -7,7 +7,7 @@
     </PropertyGroup>
 
     <ItemGroup>
-        <PackageReference Include="coverlet.msbuild" Version="2.8.0" />
+        <PackageReference Include="coverlet.msbuild" Version="2.8.1" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.5.0" />
         <PackageReference Include="Selenium.WebDriver" Version="3.141.0" />
         <PackageReference Include="xunit" Version="2.4.1" />