util/lint/lint-stable-003-whitespace: add exception for gif files

Adding gif files to the whitespace exclude list, to prevent issue where
commits were failing due to binary files.

Change-Id: I56679780348579d01c81c6f1677e4ea456315c9e
Signed-off-by: Fred Reitberger <reitbergerfred@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/61460
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/util/lint/lint-stable-003-whitespace b/util/lint/lint-stable-003-whitespace
index fd4d0e4..6f9d788 100755
--- a/util/lint/lint-stable-003-whitespace
+++ b/util/lint/lint-stable-003-whitespace
@@ -5,7 +5,7 @@
 # DESCR: Check for superfluous whitespace in the tree
 
 LC_ALL=C export LC_ALL
-EXCLUDELIST='^src/vendorcode/|^util/kconfig/|^util/nvidia/cbootimage$|COPYING|LICENSE|README|_shipped$|\.patch$|\.bin$|\.hex$|\.jpg$|\.ttf$|\.woff$|\.png$|\.eot$|\.vbt$|\.ico$'
+EXCLUDELIST='^src/vendorcode/|^util/kconfig/|^util/nvidia/cbootimage$|COPYING|LICENSE|README|_shipped$|\.patch$|\.bin$|\.hex$|\.jpg$|\.gif$|\.ttf$|\.woff$|\.png$|\.eot$|\.vbt$|\.ico$'
 INCLUDELIST="src util payloads Makefile* toolchain.inc tests"
 
 # shellcheck disable=SC2086,SC2046