Handle if no module found for bots (#564)

Co-authored-by: Taranjeet Singh <reachtotj@gmail.com>

embedchain/bots/discord.py

@@ -2,14 +2,21 @@ import argparse
 import logging
 import os
 
-import discord
-from discord import app_commands
-from discord.ext import commands
-
 from embedchain.helper.json_serializable import register_deserializable
 
 from .base import BaseBot
 
+try:
+    import discord
+    from discord import app_commands
+    from discord.ext import commands
+except ModuleNotFoundError:
+    raise ModuleNotFoundError(
+        "The required dependencies for Discord are not installed."
+        'Please install with `pip install "embedchain[discord]"`'
+    ) from None
+
+
 intents = discord.Intents.default()
 intents.message_content = True
 client = discord.Client(intents=intents)