fontforge PPA / font-patcher script errors 
#### 🎯 Subject of the issue

- Unable to enable glyph icons
- Unable to add the fontforge repository
- Unable to run font-patcher script

<!--- Describe issue here -->
Setup: Windows 11 running WSL2 on Ubuntu 20.0403, Bash shell

I have installed b-ryan's powerline-shell prompt and my goal is to enable the icon glyphs included with the package.  I tried the method of simply patching an individual font (CascadiaCode) for Microsoft without luck.  Ultimately, I cloned the nerd-fonts repository and ran the install.sh script successfully.

Whenever I cache my fonts, it appears to run successfully and showed that roughly 154 fonts were added; however, the fonts do not show up in the /.local/share/fonts directory.  At most, I was able to install CascadiaCode from Microsoft's release and change my font face within Properties -> Fonts.

I run into issues when I get to the font-forge and font-patcher steps.
When running this command I receive the following output:
`sudo add-apt-repository ppa:fontforge/fontforge;`

> Get:1 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
> Ign:2 http://ppa.launchpad.net/fontforge/fontforge/ubuntu focal InRelease
> Hit:3 http://archive.ubuntu.com/ubuntu focal InRelease
> Get:4 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
> Err:5 http://ppa.launchpad.net/fontforge/fontforge/ubuntu focal Release
>   404  Not Found [IP: 91.189.95.85 80]
> Get:6 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB]
> Reading package lists... Done
> E: The repository 'http://ppa.launchpad.net/fontforge/fontforge/ubuntu focal Release' does not have a Release file.
> N: Updating from such a repository can't be done securely, and is therefore disabled by default.
> N: See apt-secure(8) manpage for repository creation and user configuration details.

#### 🔧 Your Setup

- _Which font are you using (e.g. `Anonymice Powerline Nerd Font Complete.ttf`)?_
- CascadiaCode 
- _Which terminal emulator are you using (e.g. `iterm2`, `urxvt`, `gnome`, `konsole`)?_
- Ubuntu v 20.04.3 bash shell v. 5.0.17
- _Are you using OS X, Linux or Windows? And which specific version or distribution?_
- Windows 11 running Windows Subsytem for Linux 2 kernel

#### ★ Optional

<!--- Provide screenshots where appropriate -->
