fix(firestore): update the API

#### firestore:v1

The following keys were changed:
- resources.projects.resources.locations.methods.list.parameters.pageSize.description

discovery/firestore-v1.json

@@ -1135,7 +1135,7 @@
                   "type": "string"
                 },
                 "pageSize": {
-                  "description": "The maximum number of results to return. If not set, the service will select a default.",
+                  "description": "The maximum number of results to return. If not set, the service selects a default.",
                   "format": "int32",
                   "location": "query",
                   "type": "integer"
@@ -1160,7 +1160,7 @@
       }
     }
   },
-  "revision": "20210326",
+  "revision": "20210419",
   "rootUrl": "https://firestore.googleapis.com/",
   "schemas": {
     "ArrayValue": {

src/apis/firestore/v1.ts

@@ -6085,7 +6085,7 @@ export namespace firestore_v1 {
      *     filter: 'placeholder-value',
      *     // The resource that owns the locations collection, if applicable.
      *     name: 'projects/my-project',
-     *     // The maximum number of results to return. If not set, the service will select a default.
+     *     // The maximum number of results to return. If not set, the service selects a default.
      *     pageSize: 'placeholder-value',
      *     // A page token received from the `next_page_token` field in the response. Send that page token to receive the subsequent page.
      *     pageToken: 'placeholder-value',
@@ -6214,7 +6214,7 @@ export namespace firestore_v1 {
      */
     name?: string;
     /**
-     * The maximum number of results to return. If not set, the service will select a default.
+     * The maximum number of results to return. If not set, the service selects a default.
      */
     pageSize?: number;
     /**