[bugfix] use raw string for regexes when backslash is used (#1823)

SUMMARY:
Resolves #1776 

The `gemma3_example.py` script was not correctly escaping the `\`
character in its regexes. This adds the `r"` prefix to the string, so
that python knows it is a raw string that needs to be escaped, avoiding
warnings.

It appears to be isolated to this example, I couldn't find other regexes
with `\` characters that weren't being properly escaped.


TEST PLAN:
Example runs successfully after changes.

Signed-off-by: Brian Dellabetta <[email protected]>

Author: brian-dellabetta

examples/multimodal_vision/gemma3_example.py

@@ -32,8 +32,8 @@ def data_collator(batch):
         scheme="W4A16",
         ignore=[
             "lm_head",
-            "re:model\.vision_tower.*",
-            "re:model\.multi_modal_projector.*",
+            r"re:model\.vision_tower.*",
+            r"re:model\.multi_modal_projector.*",
         ],
     ),
 ]