[prettier] Ignore compiler/target (#31168)

Add missing directory to prettierignore.
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[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/facebook/react/pull/31168).
* #31167
* #31166
* #31165
* #31164
* #31148
* __->__ #31168

.prettierignore

@@ -24,6 +24,7 @@ compiler/**/.next
 compiler/packages/babel-plugin-react-compiler/src/__tests__/fixtures/compiler/error.todo-kitchensink.js
 
 compiler/crates
+compiler/target
 compiler/apps/playground/public
 
 compiler/**/LICENSE