Add Prepare Request support to RequestTracker and OpenTelemetry exten…

…sion (#614)

update changelog and docs yml

CSHARP-1008 Remove EOL target frameworks and add new ones (.NET 6, .N…

…ET 7, .NET 8) (#606)

- update several dependencies of the test projects
- add openssl.cnf TLS workaround to jenkinsfile
- fix build and test issues with new .NET versions
- update .NET targets of example projects
- update .NET targets in Jenkinsfile and Jenkinsfile.scheduled
- update .NET versions in appveyor and travis builds
- add readme section to describe which platforms are used in testing

3.20.0 release

fix 3.19.5 release date

bump version

3.19.3 release

update changelog and bump version

release 3.19.0