Fix parallel executions exceptions

[scasteran]

Types of changes

• Bug fix (non-breaking change which fixes an issue).
• New feature (non-breaking change which adds functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as expected).

Checklist:

• I've added tests for my code. (most of the time mandatory)
• I have added an entry to the changelog. (mandatory)
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

This MR prevents these 2 multi-thread related errors that happen randomly when running tests in parallel:

TechTalk.SpecFlow.SpecFlowException : Invalid sftemplate file! Duplicate key: 'CSharp/StepDefinitionRegex'.
   at TechTalk.SpecFlow.BindingSkeletons.FileBasedSkeletonTemplateProvider.EnsureInitialized()

System.NullReferenceException : Object reference not set to an instance of an object.
 TearDown : System.NullReferenceException : Object reference not set to an instance of an object.
    at TechTalk.SpecFlow.Infrastructure.ContextManager.InitializeScenarioContext(ScenarioInfo scenarioInfo)

[SabotageAndi]

Thanks for this fix. Sorry that it took so long for me to review.
Could you rebase the PR on master and adjust the changelog?
Please add your entry under the Fixes for Development: section. Thanks!

[SabotageAndi]

Rebase and adjust changelog please.

[scasteran]

Sorry for the branch history. Hopefully this looks good now.

[SabotageAndi]

Thanks for your contribution to SpecFlow. These flaky tests are very annoying.
If you would like us to send you some SpecFlow stickers as a thank you, please fill out the form here.