fix permissions

Author: duncanpharvey

.github/workflows/cargo.yml

@@ -7,6 +7,8 @@ on:
         required: true
         type: string
 
+permissions: {}
+
 jobs:
   setup:
     name: Setup

.github/workflows/checks.yml

@@ -10,6 +10,8 @@ on:
 
 jobs:
   cargo:
+    permissions:
+      contents: write
     strategy:
       fail-fast: false
       matrix: