Upgrade to BenchmarkDotNet 0.12.1

Author: Jericho

Source/HttpMultipartParser.Benchmark/HttpMultipartParser.Benchmark.csproj

@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="BenchmarkDotNet" Version="0.12.0" />
+    <PackageReference Include="BenchmarkDotNet" Version="0.12.1" />
   </ItemGroup>
 
   <ItemGroup>