[misc] automatically strip periods when generating changelog entries (#18598)

Manually removing the periods caused a small amount of busy work in the
1.15 release. It's easy enough to tweak the script, so I went ahead and
added a `removesuffix` call.

Author: wesleywright

misc/generate_changelog.py

@@ -145,7 +145,8 @@ def format_changelog_entry(c: CommitInfo) -> str:
         s += f" (#{c.pr_number})"
     s += f" ({c.author})"
     """
-    s = f" * {c.title} ({c.author}"
+    title = c.title.removesuffix(".")
+    s = f" * {title} ({c.author}"
     if c.pr_number:
         s += f", PR [{c.pr_number}](https://github.com/python/mypy/pull/{c.pr_number})"
     s += ")"