Make Format check safe for fork PRs (#260)

Switch the trigger from pull_request_target to pull_request and drop the
write permissions. GitHub now refuses to check out fork PR code from a
pull_request_target workflow, breaking formatting checks for external
contributors. See QuantumKitHub/.github#2.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: lkdvos

.github/workflows/FormatCheck.yml

@@ -1,14 +1,12 @@
 name: 'Format'
 
 on:
-  pull_request_target:
+  pull_request:
     paths: ['**/*.jl']
     types: [opened, synchronize, reopened, ready_for_review]
 
 permissions:
   contents: read
-  actions: write
-  pull-requests: write
 
 jobs:
   formatcheck: