Allow Lumen 5.1 to be installed.
Allow Lumen 5.1 to be installed.

Signed-off-by: crynobone <e1a543840a942eb68427510a8a483282a7bfeddf@gmail.com>

piokom123/lumen-framework,orchestral/lumen,crynobone/lumen-framework,xiphiaz/lumen-framework,cnanney/lumen-framework,rakaaditya/lumen-framework,laravel/lumen-framework,lasselehtinen/lumen-framework,callam/lumen-framework,scrubmx/lumen-framework,Beanhunter/lumen-framework,SelimSalihovic/lumen-framework,rlacerda83/lumen-framework,Jaspur/lumen-framework