update discord.py

Bumps [discord-py](https://github.com/Rapptz/discord.py) from 1.4.1 to 1.5.0.
- [Release notes](https://github.com/Rapptz/discord.py/releases)
- [Commits](Rapptz/discord.py@v1.4.1...v1.5.0)

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Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

requirements.txt

@@ -5,7 +5,7 @@ beautifulsoup4==4.9.2
 bs4==0.0.1
 certifi==2020.6.20
 chardet==3.0.4
-discord.py==1.4.1
+discord.py==1.5.0
 idna==2.10
 lavalink==3.1.2
 multidict==4.7.6