Add .Net 7 (#853)

* Add .NET 7

* UseDotNet

* 7

* Ubuntu 6

* 'Use .NET 7'

* 67

* .

* use 7

* use 7

* test = 7

* coverage.7.0.opencover.xml

azure-pipelines-ci-linux.yml

@@ -5,8 +5,16 @@ variables:
   buildConfiguration: 'Release'
 
 steps:
+- task: UseDotNet@2
+  displayName: 'Use .NET 7'
+  inputs:
+    packageType: sdk
+    version: 7.0.x
+
 - script: |
-    dotnet test ./test/WireMock.Net.Tests/WireMock.Net.Tests.csproj --configuration $(buildConfiguration) --framework net6.0 --logger trx
+    dotnet test ./test/WireMock.Net.Tests/WireMock.Net.Tests.csproj --configuration $(buildConfiguration) --framework net7.0 --logger trx
+  displayName: 'Test'
+
 - task: PublishTestResults@2
   inputs:
     testRunner: VSTest