add changelog linkifier util

test/helper_tools/linkify-changelog.py

@@ -0,0 +1,14 @@
+#!/usr/bin/env python3
+from pathlib import Path
+import re
+
+changelog = Path(__file__).parent / "../../CHANGELOG.md"
+
+text = changelog.read_text(encoding="utf8")
+text, n = re.subn(
+    r"\s*\(([^)]+)#(\d+)\)",
+    "\n  (\\1[#\\2](https://github.com/mitmproxy/mitmproxy/issues/\\2))",
+    text
+)
+changelog.write_text(text, encoding="utf8")
+print(f"Linkified {n} issues and users.")