Update to Flask 2.x, fix Werkzeug dependency issue, operator fixes

[vincebel7]

Not tied to an issue, but this fix solves three main issues I ran when setting up, tied to some outdated packages:

1. jinja2 error at runtime, fixed by moving from Flask 1.1.1 to 2.1.1

ImportError: cannot import name 'escape' from 'jinja2' (/home/venus/stuff/Multiplayer-Game-Server/venv/lib/python3.10/site-packages/jinja2/__init__.py)

2. Werkzeug error at runtime, fixed by using Werkzeug 2.x and specifying in requirements.txt

ImportError: cannot import name 'run_with_reloader' from 'werkzeug.serving' (/home/venus/stuff/Multiplayer-Game-Server/venv/lib/python3.10/site-packages/werkzeug/serving.py)

3. SyntaxWarning: "is" with a literal. Did you mean "=="? Fixed by swapping to equality operator on all five accounts

/home/venus/stuff/Multiplayer-Game-Server/server.py:61: SyntaxWarning: "is" with a literal. Did you mean "=="?

Also added venv/ to .gitignore as my aliases are set up for my venv to be named such.