Chore: Drop support for Python 3.8

Python 3.8 was EoL @ 2024-10-07, our 6 month promise for support will end @ 2024-04-07.
This PR removes all unnecessary references and modifies the baseline references to 3.9.
Outdated python syntax was updated with pyupgrade.

Author: jomcgi

.github/ISSUE_TEMPLATE/bug_report.yaml

@@ -18,7 +18,7 @@ body:
         Please describe any aspect of your environment relevant to the problem, including your Python version, [platform](https://docs.python.org/3/library/platform.html), version numbers of installed dependencies, information about your cloud hosting provider, etc. If you're reporting a problem with a specific version of a library in this repo, please check whether the problem has been fixed on main.
       value: |
         OS: (e.g, Ubuntu)
-        Python version: (e.g., Python 3.8.10)
+        Python version: (e.g., Python 3.9.10)
         Package version: (e.g., 0.46.0)
   
   - type: textarea