Change Gallery block code ownership (#38722)

* Remove mkevins from Gallery block codeowners

* Add @geriux as codeowner for the gallery block

Co-authored-by: Gerardo <gerardo.pacheco@automattic.com>

.github/CODEOWNERS

@@ -14,7 +14,7 @@
 
 # Blocks
 /packages/block-library                         @ajitbohra
-/packages/block-library/src/gallery             @mkevins
+/packages/block-library/src/gallery             @geriux
 /packages/block-library/src/social-links        @mkaz
 /packages/block-library/src/social-link         @mkaz
 /packages/block-library/src/navigation          @tellthemachines