fix(recommendationengine): update the API

#### recommendationengine:v1beta1

The following keys were changed:
- schemas.GoogleCloudRecommendationengineV1beta1PredictRequest.properties.params.description

discovery/recommendationengine-v1beta1.json

@@ -842,7 +842,7 @@
       }
     }
   },
-  "revision": "20210409",
+  "revision": "20210514",
   "rootUrl": "https://recommendationengine.googleapis.com/",
   "schemas": {
     "GoogleApiHttpBody": {
@@ -1460,7 +1460,7 @@
           "additionalProperties": {
             "type": "any"
           },
-          "description": "Optional. Additional domain specific parameters for the predictions. Allowed values: * `returnCatalogItem`: Boolean. If set to true, the associated catalogItem object will be returned in the `PredictResponse.PredictionResult.itemMetadata` object in the method response. * `returnItemScore`: Boolean. If set to true, the prediction 'score' corresponding to each returned item will be set in the `metadata` field in the prediction response. The given 'score' indicates the probability of an item being clicked/purchased given the user's context and history. * `strictFiltering`: Boolean. True by default. If set to false, the service will return generic (unfiltered) popular items instead of empty if your filter blocks all prediction results.",
+          "description": "Optional. Additional domain specific parameters for the predictions. Allowed values: * `returnCatalogItem`: Boolean. If set to true, the associated catalogItem object will be returned in the `PredictResponse.PredictionResult.itemMetadata` object in the method response. * `returnItemScore`: Boolean. If set to true, the prediction 'score' corresponding to each returned item will be set in the `metadata` field in the prediction response. The given 'score' indicates the probability of an item being clicked/purchased given the user's context and history. * `strictFiltering`: Boolean. True by default. If set to false, the service will return generic (unfiltered) popular items instead of empty if your filter blocks all prediction results. * `priceRerankLevel`: String. Default empty. If set to be non-empty, then it needs to be one of {'no-price-reranking', 'low-price-reranking', 'medium-price-reranking', 'high-price-reranking'}. This gives request level control and adjust prediction results based on product price. * `diversityLevel`: String. Default empty. If set to be non-empty, then it needs to be one of {'no-diversity', 'low-diversity', 'medium-diversity', 'high-diversity', 'auto-diversity'}. This gives request level control and adjust prediction results based on product category.",
           "type": "object"
         },
         "userEvent": {