You can use the set_image()
function passing an url to your image to set the embed image to the one you want.
embed = discord.Embed(title="Title", description="Description", color=0x00ff00)
embed.add_field(name="Field1", value="test", inline=False)
embed.set_image(url="https://url-to-your-picture.gif")
await message.channel.send(embed=embed)
References:
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…