chore(changelog): append to CHANGELOG.md instead of overwriting

Author: g1331

Diff for: utils/bump.py

@@ -98,7 +98,7 @@ def get_base_version(version: str) -> str:
 
 
 def generate_changelog(version: str):
-    cmd = ["git-cliff", "--tag", f"v{version}", "-o", "CHANGELOG.md"]
+    cmd = ["git-cliff", "--tag", f"v{version}", "--append", "-o", "CHANGELOG.md"]
     try:
         result = subprocess.run(cmd, capture_output=True, text=True)
         if result.returncode != 0: