ReplSet option using Mongo memory server
Hi! 👋 

Today I used [patch-package](https://github.com/ds300/patch-package) to patch `@tsed/testing-mongoose@6.116.5` for the project I'm working on.

We are using transactions and sessions. To do testing around this we need to use the ReplSet in mongo memory server. Is there a way we could choose if we wanted to use the ReplSet vs the standalone? 

Here is the diff that solved my problem:

```diff
diff --git a/node_modules/@tsed/testing-mongoose/lib/cjs/TestMongooseContext.js b/node_modules/@tsed/testing-mongoose/lib/cjs/TestMongooseContext.js
index 01b4037..b63b353 100644
--- a/node_modules/@tsed/testing-mongoose/lib/cjs/TestMongooseContext.js
+++ b/node_modules/@tsed/testing-mongoose/lib/cjs/TestMongooseContext.js
@@ -17,7 +17,7 @@ class TestMongooseContext extends common_1.PlatformTest {
     static async install(options = { binary: {} }) {
         if (!TestMongooseContext.getMongo()) {
             // @ts-ignore
-            global.__MONGOD__ = new mongodb_memory_server_1.MongoMemoryServer({
+            global.__MONGOD__ = new mongodb_memory_server_1.MongoMemoryReplSet({
                 ...options,
                 binary: {
                     ...(options.binary || {}),
```
