[FIX] survey: fix the function extract comment from the answers

Steps to follow to reproduce the bug:
	-Go to survey
	-Choose any survey with at least one "single text box" question
	-In the survey form
	-Click on the button test
	-Complete the survey, but in a "single text box" question, write the word "comment"
	-Validate the survey
	-An error is triggered.

Problem :
In the function which extracts comments from answers, it doesn't check the type in which the answer is stored.
When there is a comment, it is stored in a dict under the key: "comment".
To find the comment, the function checks if "comment"(key) is in the answer.
But in the case of "single text box" question, the answer is stored in a string.
If the word "comment" is present in the answer, the function looking for the key "comment" will return True and try to extract the comment.

Solution :
Add a check to ensure that we are looking for the key "comment" in dict type.

opw-2446194

closes odoo/odoo#67002

X-original-commit: 7064d46a804ab86d1bc50d003b8ae63490a1ef9c
Signed-off-by: Anh Thao PHAM <kitan191@users.noreply.github.com>
Signed-off-by: Djamel Touati <DjamelTouati@users.noreply.github.com>

addons/survey/controllers/main.py

@@ -535,7 +535,7 @@ class Survey(http.Controller):
                 if not isinstance(answers, list):
                     answers = [answers]
                 for answer in answers:
-                    if 'comment' in answer:
+                    if isinstance(answer, dict) and 'comment' in answer:
                         comment = answer['comment'].strip()
                     else:
                         answers_no_comment.append(answer)