Update azuredeploy_MimecastAudit_AzureFunctionApp.json

Solutions/MimecastAudit/Data Connectors/azuredeploy_MimecastAudit_AzureFunctionApp.json

@@ -209,7 +209,7 @@
           ],
           "properties": {
             "AzureWebJobsStorage": "[concat('DefaultEndpointsProtocol=https;AccountName=', variables('storageAccountName'), ';EndpointSuffix=', environment().suffixes.storage, ';AccountKey=',listKeys(resourceId('Microsoft.Storage/storageAccounts', variables('storageAccountName')), '2019-06-01').keys[0].value)]",
-            "FUNCTIONS_EXTENSION_VERSION": "~3",
+            "FUNCTIONS_EXTENSION_VERSION": "~4",
             "FUNCTIONS_WORKER_RUNTIME": "python",
             "APPINSIGHTS_INSTRUMENTATIONKEY": "[reference(resourceId('microsoft.insights/components', variables('applicationInsightsName')), '2020-02-02-preview').InstrumentationKey]",
             "mimecast_email": "[concat('@Microsoft.KeyVault(SecretUri=https://', variables('functionAppName'), '.vault.azure.net/secrets/', 'mimecast-email', '/)')]",