Update travis setup for composer 2.

Signed-off-by: Mior Muhammad Zaki <[email protected]>

Allows serializing global scopes.

Fixes laravie#3

Signed-off-by: Mior Muhammad Zaki <[email protected]>

Improves tests.

Signed-off-by: Mior Muhammad Zaki <[email protected]>

Prefer-stable.

Signed-off-by: Mior Muhammad Zaki <[email protected]>

Store deleted scoped.

Signed-off-by: Mior Muhammad Zaki <[email protected]>