fix: Don't ignore Yarn patch files (#25398)

An earlier commit modified `.gitignore` to ignore `.yarn` files in
`development/generate-attributions` (which is a special sub-project in
this repo used in the attribution generation workflow). However, this
change ended up ignoring Yarn patch files in `.yarn/patches` (along with
possibly other Yarn-specific files). This commit narrows the pattern in
`.gitignore` not to do this.

.gitignore

@@ -55,13 +55,14 @@ test-results/
 # This file is used to authenticate with the GitHub Package registry, to
 # enable the use of @metamask preview builds.
 .npmrc
-#yarn
+
+# Yarn
 .yarn/*
 !.yarn/patches
 !.yarn/plugins
 !.yarn/sdks
 !.yarn/versions
-**/.yarn/*
+development/generate-attributions/.yarn/*
 
 # MMI Playwright
 public/playwright