build(deps): bump python from 3.8.6-slim to 3.9.0-slim in /bot

Bumps python from 3.8.6-slim to 3.9.0-slim.

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

bot/Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.8.6-slim
+FROM python:3.9.0-slim
 
 ADD tools /src/tools
 ADD bot /src/bot