chore: upgrade ShadowJar.
chore: upgrade ShadowJar.

Summary: Gradle v2.12 is incompatible with ShadowJar 1.2.2.

Reviewers: rkirov

Reviewed By: rkirov

Subscribers: typescript-eng

Differential Revision: https://reviews.angular.io/D36

angular/clutz,polybuildr/clutz,rehmsen/clutz,dpurp/clutz,angular/clutz,angular/clutz,dpurp/clutz,dpurp/clutz,rehmsen/clutz,polybuildr/clutz,rehmsen/clutz,polybuildr/clutz