diff --git a/CHANGES.md b/CHANGES.md
index ba7947a..d7928a3 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -70,6 +70,8 @@
 <!-- For example, Docker, GitHub Actions, pre-commit, editors -->
 
 - Update GitHub Action to display black output in the job summary (#3688)
+- Deprecated `set-output` command in CI test to keep up to date with GitHub's
+  deprecation announcement (#3757)
 
 ### Documentation
 
diff --git a/scripts/diff_shades_gha_helper.py b/scripts/diff_shades_gha_helper.py
index b5fea5a..994fbe0 100644
--- a/scripts/diff_shades_gha_helper.py
+++ b/scripts/diff_shades_gha_helper.py
@@ -52,7 +52,13 @@ def set_output(name: str, value: str) -> None:
         print(f"[INFO]: setting '{name}' to '{value}'")
     else:
         print(f"[INFO]: setting '{name}' to [{len(value)} chars]")
-    print(f"::set-output name={name}::{value}")
+
+    # Originally the `set-output` workflow command was used here, now replaced
+    # by setting variables through the `GITHUB_OUTPUT` environment variable
+    # to stay up to date with GitHub's update.
+    if "GITHUB_OUTPUT" in os.environ:
+        with open(os.environ["GITHUB_OUTPUT"], "a") as f:
+            print(f"{name}={value}", file=f)
 
 
 def http_get(url: str, *, is_json: bool = True, **kwargs: Any) -> Any: