package:build_test v3.4.0

• Support post process builders in testBuilders. And, add appliesBuilders
  so that builders can apply post process builders.
• Add testBuilderFactories: like testBuilders, but provide the builder
  factories instead of the builders. Use this to allow config read from
  build.yaml to be passed in to the factory.
• TestBuilder now accepts a name: this is the name that will be shown
  in logging and can be used to refer to the builder in build.yaml.
• More realistic test builds: in resolveSources and testBuilders, stop
  builders reading from .dart_tool.
• Bug fix: in testBuilders, configure the root package correctly when it
  has no sources.
• Use build_runner_core 9.4.0.
• Remove unused dep: build_resolvers.
• Remove unused dep: build_runner_core.