#2457 - Adding a line to build pipeline to purge pip cache. Seeing if this could resolve hash error seen on some pipeline failures

.azure/azure-ci-build-pipeline.yaml

@@ -87,6 +87,7 @@ stages:
             condition: or(eq( variables['Agent.OS'], 'Linux' ), eq( variables['Agent.OS'], 'Darwin' ))
 
           - script: |
+              pip cache purge
               forfiles /p dist\ /m *.whl /c "cmd /c python -m pip install --no-cache-dir @file[dev]"
             displayName: 'Install PrimAITE'
             condition: eq( variables['Agent.OS'], 'Windows_NT' )