revert pester changes in this PR

Author: JimSuplizio

eng/common/pipelines/templates/steps/run-pester-tests.yml

@@ -13,7 +13,7 @@ parameters:
 
 steps:
   - pwsh: |
-       Install-Module -Name Pester -RequiredVersion 5.5.0 -Force
+       Install-Module -Name Pester -Force
     displayName: Install Pester
 
    # default test steps