Don't trim whitespace at beginning of cell code in the REPL

Co-authored-by: Elliott Gordon-Rodriguez <egr95@users.noreply.github.com>
Co-authored-by: matteha <matteha@users.noreply.github.com>

closes #252
closes #280

* jupyter-repl.el (jupyter-repl-execute-cell): Do it.

Author: nnicandro

jupyter-repl.el

@@ -833,7 +833,7 @@ Return the `jupyter-request' representing the executed code."
     (save-excursion
       (goto-char (jupyter-repl-cell-code-beginning-position))
       (run-hooks 'jupyter-repl-cell-pre-send-hook))
-    (let ((code (string-trim (jupyter-repl-cell-code))))
+    (let ((code (string-trim (jupyter-repl-cell-code) "[\r\n]+")))
       (jupyter-run-with-client client
         (jupyter-mlet* ((req (jupyter-execute-request
                               :code code