chore: fix zizmor findings

Author: branchv

.github/workflows/main.yaml

@@ -10,6 +10,8 @@ concurrency:
   group: tests-${{ github.head_ref || github.ref }}
   cancel-in-progress: ${{ github.event_name == 'pull_request' }}
 
+permissions: {}
+
 jobs:
   tests:
     name: ${{ matrix.os }} / ${{ matrix.python-version }} ${{ matrix.suffix }}

.github/workflows/release.yaml

@@ -4,6 +4,8 @@ on:
   release:
     types: [published]
 
+permissions: {}
+
 jobs:
   build:
     name: Build