Your requirements could not be resolved to an installable set of packages

[emmylexo]

I tried adding this package to my project and it gave me the error below

Problem 1
- Root composer.json requires lightit/linkedin-share dev-master -> satisfiable by lightit/linkedin-share[dev-master].
- lightit/linkedin-share dev-master requires guzzlehttp/guzzle ^6.3 -> found guzzlehttp/guzzle[6.3.0, ..., 6.5.x-dev] but it conflicts with your root composer.json require (^7.0.1).

Use the option --with-all-dependencies (-W) to allow upgrades, downgrades and removals for packages currently locked to specific versions.

Please I will need some help