Update .ps1 file to use coveralls.net v 3.0.0 (#6310)

build/PublishToCoveralls.ps1

@@ -11,7 +11,7 @@ Param(
 Write-Host Install tools
 $basePath = (get-item $pathToCoverageFiles ).parent.FullName
 $coverageAnalyzer = "C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Team Tools\Dynamic Code Coverage Tools\CodeCoverage.exe"
-dotnet tool install coveralls.net --version 1.0.0 --tool-path tools --add-source https://api.nuget.org/v3/index.json
+dotnet tool install coveralls.net --version 3.0.0 --tool-path tools --add-source https://api.nuget.org/v3/index.json
 $coverageUploader = ".\tools\csmacnz.Coveralls.exe"
 
 # Download temporary version of Archive module that fixes issue on macOS/Linux with path separator

build/yaml/ci-test-steps.yml

@@ -58,13 +58,6 @@ steps:
   continueOnError: true
   condition: and(succeeded(), eq(variables['PublishCoverage'], 'true'), ne(variables['System.PullRequest.IsFork'], 'True'))
 
-- task: UseDotNet@2
-  displayName: 'Use .NET Core sdk 2.1, required for Upload Coverage Files task'
-  inputs:
-    packageType: sdk
-    version: 2.1.x
-  condition: and(succeeded(), eq(variables['PublishCoverage'], 'true'), ne(variables['System.PullRequest.IsFork'], 'True'))
-
 - task: PowerShell@2
   displayName: 'Upload Coverage Files to Coveralls.io https://coveralls.io/github/microsoft/botbuilder-dotnet'
   inputs: