ci: fix magic-nix-cache write permissions

Author: outfoxxed

.github/workflows/build.yml

@@ -9,6 +9,9 @@ jobs:
         qtver: [qt6.9.2, qt6.9.1, qt6.9.0, qt6.8.3, qt6.8.2, qt6.8.1, qt6.8.0, qt6.7.3, qt6.7.2, qt6.7.1, qt6.7.0, qt6.6.3, qt6.6.2, qt6.6.1, qt6.6.0]
         compiler: [clang, gcc]
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
     steps:
       - uses: actions/checkout@v4
       # Use cachix action over detsys for testing with act.

.github/workflows/lint.yml

@@ -5,6 +5,9 @@ jobs:
   lint:
     name: Lint
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write
     steps:
       - uses: actions/checkout@v4
       # Use cachix action over detsys for testing with act.