Preserve original line ending style in lockfile metadata replacement

Address code review feedback: detect and preserve the original line ending
style (CRLF or LF) when replacing python-versions in lockfile metadata,
instead of hardcoding LF.

Co-authored-by: AbhishekBhaskar <22154418+AbhishekBhaskar@users.noreply.github.com>

Author: Copilot

python/lib/dependabot/python/file_updater/poetry_file_updater.rb

@@ -143,7 +143,9 @@ def updated_lockfile_content
               original_locked_python = TomlRB.parse(T.must(lockfile).content)["metadata"]["python-versions"]
 
               new_lockfile.gsub!(/\[metadata\](?:\r?\n).*python-versions[^\r\n]+(?:\r?\n)/m) do |match|
-                match.gsub(/(["']).*(['"])(?:\r?\n)\Z/, '\1' + original_locked_python + '\1' + "\n")
+                # Detect the line ending style from the match (CRLF or LF)
+                line_ending = match.include?("\r\n") ? "\r\n" : "\n"
+                match.gsub(/(["']).*(['"])(?:\r?\n)\Z/, '\1' + original_locked_python + '\1' + line_ending)
               end
 
               tmp_hash =