fix(#90): ensure three backticks in comments do not break markdown snippets (#91)

Author: scastlara

src/lgtm_ai/ai/prompts.py

@@ -101,7 +101,7 @@ def _get_full_category_explanation() -> str:
     - Evaluate whether some comments are more likely to simply be incorrect. If they are likely to be incorrect, remove them.
     - Merge duplicate comments. If there are two comments that refer to the same issue, merge them into one.
     - Comments have a code snippet that they refer to. Consider whether the snippet needs a bit more code context, and if so, expand the snippet. Otherwise don't touch them.
-    - If you can add a suggestion code snippet to the comment text, do it. Use markdown code blocks. Do it only when you are very sure about the suggestion with the context you have.
+    - If you can add a suggestion code snippet to the comment text, do it. Use markdown code blocks with 5 backticks. Do it only when you are very sure about the suggestion with the context you have.
     - Check that categories of each comment are correct. Re-categorize them if needed.
     - Check the summary. Feel free to rephrase it, add more information, or generally improve it. The summary comment must be a general comment informing the PR author about the overall quality of the PR, the weakpoints it has, and which general issues need to be addressed.
 

src/lgtm_ai/formatters/templates/snippet.md.j2

@@ -1,3 +1,3 @@
-```{{ language }}
+`````{{ language }}
 {{ snippet | safe }}
-```
+`````

tests/formatters/test_markdown.py

@@ -214,9 +214,9 @@ def test_format_comment_with_snippet(self) -> None:
             "> **Severity:** LOW 🔵",
             "",
             "",
-            "```python",
+            "`````python",
             "print('Hello World')",
-            "```",
+            "`````",
             "",
             "",
             "comment",