Public key failure for docker windows build

[oxr463]

Describe the bug
A clear and concise description of what the bug is.

+ wget -nv https://dl.winehq.org/wine-builds/Release.key
2020-06-25 14:07:31 URL:https://dl.winehq.org/wine-builds/Release.key [3122/3122] -> "Release.key" [1]
+ apt-key add Release.key
OK
+ add-apt-repository https://dl.winehq.org/wine-builds/ubuntu/
+ apt-get update -qy
Hit:1 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:2 http://archive.ubuntu.com/ubuntu xenial InRelease
Get:3 https://dl.winehq.org/wine-builds/ubuntu xenial InRelease [6259 B]
Hit:4 http://archive.ubuntu.com/ubuntu xenial-updates InRelease
Ign:3 https://dl.winehq.org/wine-builds/ubuntu xenial InRelease
Get:5 https://dl.winehq.org/wine-builds/ubuntu xenial/main amd64 Packages [1080 kB]
Hit:6 http://archive.ubuntu.com/ubuntu xenial-backports InRelease
Get:7 https://dl.winehq.org/wine-builds/ubuntu xenial/main i386 Packages [1141 kB]
Fetched 2227 kB in 1s (1937 kB/s)
Reading package lists...
W: GPG error: https://dl.winehq.org/wine-builds/ubuntu xenial InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 76F1A20FF987672F
W: The repository 'https://dl.winehq.org/wine-builds/ubuntu xenial InRelease' is not signed.
+ apt-get install --no-install-recommends -qfy winehq-staging winbind cabextract
[ . . . TRUNCATED . . . ]
After this operation, 1067 MB of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
  wine-staging-i386:i386 wine-staging-amd64 wine-staging winehq-staging
E: There were unauthenticated packages and -y was used without --allow-unauthenticated

To Reproduce

docker build -t gdbgui_windows docker/windows

Expected behavior
A clear and concise description of what you expected to happen.

For the binary to build.

Screenshots
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See log output above.

Please complete the following information:

• OS: Docker
• gdbgui version (gdbgui -v): master
• gdb version (gdb -v): N/A
• browser [e.g. chrome, safari]: N/A
• python packages (pip freeze): N/A

Additional context
Add any other context about the problem here.

[cs01]

Docker files were removed. GitHub actions are now used for windows builds.