Add write permissions to release process (bytecodealliance#1047)

Looks like releases won't work without this any more

Author: alexcrichton

.github/workflows/release-process.yml

@@ -16,6 +16,9 @@ on:
         required: false
         default: 'bump'
 
+permissions:
+  contents: write
+
 jobs:
   release_process:
     name: Run the release process