refactor(changelog): use set to check if a GitTag is used

Author: bearomorphism

commitizen/changelog.py

@@ -102,7 +102,7 @@ def generate_tree_from_commits(
         current_tag_date = current_tag.date
 
     changes: defaultdict[str | None, list] = defaultdict(list)
-    used_tags = [current_tag]
+    used_tags: set[GitTag | None] = set([current_tag])
     for commit in commits:
         commit_tag = get_commit_tag(commit, tags)
 
@@ -111,7 +111,7 @@ def generate_tree_from_commits(
             and commit_tag not in used_tags
             and rules.include_in_changelog(commit_tag)
         ):
-            used_tags.append(commit_tag)
+            used_tags.add(commit_tag)
             release = {
                 "version": current_tag_name,
                 "date": current_tag_date,

commitizen/git.py

@@ -41,6 +41,9 @@ def __eq__(self, other) -> bool:
             return False
         return self.rev == other.rev  # type: ignore
 
+    def __hash__(self):
+        return hash(self.rev)
+
 
 class GitCommit(GitObject):
     def __init__(