Add latency command

app/modules/latency.py

@@ -0,0 +1,9 @@
+import niobot
+
+
+class LatencyModule(niobot.Module):
+    @niobot.command("latency")
+    async def latency(self, ctx: niobot.Context):
+        """See the bot's latency."""
+        latency = ctx.latency
+        return await ctx.respond("Latency: {:.2f}ms".format(latency * 1000))