Increase elastic apm dependency version in Elastic.Apm.SerilogEnricher

[gregkalapos]

In order to fix #58 I opened elastic/apm-agent-dotnet#753 in the .NET APM Agent repo.

That'll fix the issue, but we also have to make sure that Elastic.Apm.SerilogEnricher forces users to use the latest agent, otherwise they'll run into the same bug.

So, once the next APM .NET Agent version is out which contains elastic/apm-agent-dotnet#753, we need to update Elastic.Apm.SerilogEnricher.csproj and make sure Elastic.Apm.SerilogEnricher depends on the version with the fix.

[codebrain]

Makes sense @gregkalapos , if you want to ping in here when it is ready I can handle the increment and publishing.

We have some releases in the pipeline for:

1.4.3 - https://github.com/elastic/ecs-dotnet/pulls?q=is%3Apr+is%3Aopen+label%3Av1.4.3
1.5.0 - https://github.com/elastic/ecs-dotnet/pulls?q=is%3Apr+is%3Aopen+label%3Av1.5.0

So will need to ensure this is coordinated properly.

[ffMathy]

I guess it is ready now right?

[gregkalapos]

Right, Elastic APM 1.4.0 is out which has the fix.
I opened #66.