fix: `package.json#license` should be Apache

[agilgur5]

Motivation

• it was listed as MIT for some reason (copy+paste?), while Argo uses Apache, including this repo's own LICENSE file
  • also CNCF uses Apache

Modifications

• fix package.json#license field

[agilgur5]

Seems like CD corrected this in the past too: https://github.com/argoproj/argo-cd/commit/b1b5ce211eedfb9354f7661b23b60469f9b103d7