Connection::Buffer: Handle Python doc string correctly

In Python, a so-called doc string consists of a string encoded in three quote (starting and ending with """ or '''). These strings were not yet recognized correctly, so that line breaks there would cause further trouble with recognizing individual lines (which is important for the linter translation).

lib/runner/connection/buffer.rb

@@ -6,7 +6,7 @@ class Runner::Connection::Buffer
   # substring either in single or double quotes (e.g., within a JSON). Originally, each line break consists of `\r\n`.
   # We keep the `\r` at the end of the line (keeping "empty" lines) and replace it after buffering.
   # Inspired by https://stackoverflow.com/questions/13040585/split-string-by-spaces-properly-accounting-for-quotes-and-backslashes-ruby
-  SPLIT_INDIVIDUAL_LINES = /(?:"(?:\\"|[^"])*"|'(?:\\'|[^'])*'|(?:[^\r\n]|\r(?=\n)))+/
+  SPLIT_INDIVIDUAL_LINES = /(?:"""(?:\\"|[^"])*"""|"(?!"")(?:\\"|[^"])*"|''(?:\\'|[^'])*'''|'(?!'')(?:\\'|[^'])*'|(?:[^\r\n]|\r(?=\n)))+/
 
   def initialize
     @global_buffer = +''