Fix expansion for i3lock "screen" argument

"screen" is never defined so the expansion always fails. The expanded
form would have also passed an "-i" argument again so no image would
have been loaded.

Release: v4.3.0

Merge pull request #395 from betterlockscreen/bugfix_389_v420

Bugfix #389 - Prepare v4.2.0

Merge branch 'main' into next

Merge pull request #336 from betterlockscreen/next

MR for v4.0.4 release

Merge pull request #286 from betterlockscreen/next

Prepare for v4.0.3 release

Prepare beta-release for v4.0.3-beta1

Merge pull request #278 from pavanjadhaw/fix/missing_dollar_variable

Fix missing dollar for variable in cmd_exists check

Merge pull request #275 from pavanjadhaw/next

Stable Release

Prepare release v4.0.0-beta2 with autodetection of i3lock-color binar…

…y-name (i3lock-color/i3lock)