bazel_roll: Remove unused struct type

Change-Id: I5b4941769121a75b4b214b6c43267e2e1c99c04b
Reviewed-on: https://pigweed-review.googlesource.com/c/infra/recipes/+/234835
Commit-Queue: Auto-Submit <auto-submit@pigweed-service-accounts.iam.gserviceaccount.com>
Reviewed-by: Taylor Cramer <cramertj@google.com>
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Lint: Lint 🤖 <android-build-ayeaye@system.gserviceaccount.com>
Presubmit-Verified: CQ Bot Account <pigweed-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/recipe_modules/bazel_roll/api.py b/recipe_modules/bazel_roll/api.py
index 5fa2bb4..ec8c439 100644
--- a/recipe_modules/bazel_roll/api.py
+++ b/recipe_modules/bazel_roll/api.py
@@ -35,16 +35,8 @@
     from RECIPE_MODULES.pigweed.roll_util import api as roll_util_api
 
 
-@dataclasses.dataclass
-class RevisionChange:
-    old: str
-    new: str
-
-
 class BazelRollApi(recipe_api.RecipeApi):
 
-    RevisionChange = RevisionChange
-
     def workspace_path(
         self,
         root: config_types.Path,