[FIX] mail: missing attachment icon

Since 1d766c06 the attachment icon was
missing when it wasn't a pdf or image type file.

opw-2064128

closes odoo/odoo#37616

X-original-commit: de13174c
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/mail/static/src/scss/thread.scss

@@ -169,7 +169,7 @@
                 display: inline-block;
                 word-break: break-all;
             }
-            img {
+            :not(.o_image_box) > img {
                 max-width: 100%;
                 height: auto;
             }