New formula: ruby-install

Closes #20610.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
Dart 24160

Closes #20613.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>
luarocks 2.0.13

also add a 'head' declaration to support brew install --HEAD

Closes #20618.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>