ci: remove aarch64-linux runner from cachix workflow

Author: sigma

.github/workflows/cachix.yml

@@ -14,8 +14,6 @@ jobs:
         include:
           - system: x86_64-linux
             runner: ubuntu-latest
-          - system: aarch64-linux
-            runner: ubuntu-latest-arm
     runs-on: ${{ matrix.runner }}
     steps:
       - uses: actions/checkout@v4