Update GitHub actions upload-artifact to v4

Increment version to 0.4.2

Only send Discord webhook on main branch build

Increment version to 0.4.1

Merge branch 'release'

Increment version to v0.4.0-RC6

Increment version to 0.4.0-RC5

Organise desktop build, increment version to 0.4.0-RC4

Increment version to 0.4.0-RC3

Increment version to 0.4.0-RC2