Remove unused dep on package:stack_trace (dart-archive/test_descriptor#26)

Author: natebosch

pkgs/test_descriptor/pubspec.yaml

@@ -13,7 +13,6 @@ dependencies:
   matcher: '^0.12.0'
   meta: '^1.1.7'
   path: '^1.0.0'
-  stack_trace: '^1.0.0'
   test: '^1.6.0'
   term_glyph: '^1.0.0'