Reverse and format the archived changelogs (astral-sh#12099)

I think it's important for the breaking changes to be at the _top_ of
the file instead of the bottom.

Now that it's not being rendered by GitHub's Releases markdown, we can
remove the prettier ignores.

Author: zanieb

changelogs/0.1.x.md

@@ -0,0 +1,56 @@
+"""
+Reverse the ordering of versions in a changelog file, i.e., when archiving a changelog.
+"""
+
+import re
+import sys
+
+
+def parse_changelog(content):
+    """Parse the changelog content into individual version blocks."""
+    # Use regex to split the content by version headers
+    version_pattern = r"(?=## \d+\.\d+\.\d+)"
+    version_blocks = re.split(version_pattern, content)
+
+    # First item in the list is the header, which we want to preserve
+    header = version_blocks[0]
+    version_blocks = version_blocks[1:]
+
+    return header, version_blocks
+
+
+def reverse_changelog(content):
+    """Reverse the order of version blocks in the changelog."""
+    header, version_blocks = parse_changelog(content)
+
+    # Reverse the version blocks
+    reversed_blocks = version_blocks[::-1]
+
+    # Combine the header and reversed blocks
+    reversed_content = header + "".join(reversed_blocks)
+
+    return reversed_content
+
+
+def main():
+    if len(sys.argv) < 2:
+        print("Usage: reverse-changelog.py <changelog-file>")
+        sys.exit(1)
+
+    # Read the input file
+    name = sys.argv[1]
+    with open(name, "r") as file:
+        content = file.read()
+
+    # Reverse the changelog
+    reversed_content = reverse_changelog(content)
+
+    # Write the output to a new file
+    with open(name, "w") as file:
+        file.write(reversed_content)
+
+    print(f"Updated {name}")
+
+
+if __name__ == "__main__":
+    main()