I ran python3 -m pip install -U discord.py but it only installed discord.py v0.16.x. How do I install the new discord.py rewrite v1.0? 
I uninstalled the old discord.py using pip uninstall discord.py and re-ran pip to install discord.py, only to get version v0.16.x again instead of the new v1.0 version.
Go to python.org and click on download python.

Now, open and run it. Make sure you add python to the path. Click on Install. Once installed you can close it.

Go to git-scm.com and click on Download for Windows.

Once installed open it. Make sure Use git from windows command prompt is selected.
Then after clicking on next on everything, click on install.

Once install is finished, hit finish.

Copy your script address. In my case, it was Local//Programs//Python//Python39//Scripts

Open your command prompt and type cd Local//Programs//Python//Python39//Scripts. Paste your address there, mine will not work for you. Hit Enter.

Then type py -3 -m pip install -U discord.py. Hit enter again. Once the install is finished close the command prompt.


Now you are ready to go ;)
How to install discord.py rewrite?