"generator_location" rule param should not be included in hash

[thirtyseven]

Rules generated by macros will automatically have a param like this:

  generator_location = "path/to/BUILD:107:12",

This means that the hash of a target generated by a macro will change whenever its line number changes, even if nothing changed that could affect the build. bazel-contrib/target-determinator currently handles this by redacting this parameter, it seems like bazel-diff should do the same.