chore: fix fastify deprecation warning about querystringParser (#8876)

Author: nflaig

packages/api/test/utils/utils.ts

@@ -8,7 +8,9 @@ import {ApplicationMethods, addSszContentTypeParser} from "../../src/utils/serve
 export function getTestServer(): {server: FastifyInstance; start: () => Promise<string>} {
   const server = fastify({
     ajv: {customOptions: {coerceTypes: "array"}},
-    querystringParser: (str) => parseQueryString(str, {comma: true, parseArrays: false}),
+    routerOptions: {
+      querystringParser: (str) => parseQueryString(str, {comma: true, parseArrays: false}),
+    },
   });
 
   addSszContentTypeParser(server);

packages/beacon-node/src/api/rest/base.ts

@@ -73,15 +73,17 @@ export class RestApiServer {
     const server = fastify({
       logger: false,
       ajv: {customOptions: {coerceTypes: "array"}},
-      querystringParser: (str) =>
-        parseQueryString(str, {
-          // Array as comma-separated values must be supported to be OpenAPI spec compliant
-          comma: true,
-          // Drop support for array query strings like `id[0]=1&id[1]=2&id[2]=3` as those are not required to
-          // be OpenAPI spec compliant and results are inconsistent, see https://github.com/ljharb/qs/issues/331.
-          // The schema validation will catch this and throw an error as parsed query string results in an object.
-          parseArrays: false,
-        }),
+      routerOptions: {
+        querystringParser: (str) =>
+          parseQueryString(str, {
+            // Array as comma-separated values must be supported to be OpenAPI spec compliant
+            comma: true,
+            // Drop support for array query strings like `id[0]=1&id[1]=2&id[2]=3` as those are not required to
+            // be OpenAPI spec compliant and results are inconsistent, see https://github.com/ljharb/qs/issues/331.
+            // The schema validation will catch this and throw an error as parsed query string results in an object.
+            parseArrays: false,
+          }),
+      },
       bodyLimit: opts.bodyLimit,
       http: {maxHeaderSize: opts.headerLimit},
     });

packages/light-client/test/utils/server.ts

@@ -21,7 +21,9 @@ export async function startServer(
   const server = fastify({
     logger: false,
     ajv: {customOptions: {coerceTypes: "array"}},
-    querystringParser: (str) => parseQueryString(str, {comma: true, parseArrays: false}),
+    routerOptions: {
+      querystringParser: (str) => parseQueryString(str, {comma: true, parseArrays: false}),
+    },
   });
 
   addSszContentTypeParser(server);