Switch to self-hosted runner.

.github/actionlint.yml

@@ -1,5 +1,3 @@
 self-hosted-runner:
   labels:
-    - nscloud-ubuntu-20.04-amd64-8x8-with-cache
-    - nscloud-cache-tag-obscuravpn-api
-    - nscloud-cache-size-20gb
+    - nix

.github/workflows/checks.yml

@@ -1,38 +1,21 @@
 name: Checks
 
 on:
+  push: {}
   workflow_dispatch:
-  pull_request:
-    branches:
-      - '**'
-  push:
-    branches:
-      - 'v0'
 
 jobs:
   build_all:
     name: Build All
-    runs-on:
-      # https://namespace.so/docs/features/faster-github-actions#using-runner-labels
-      - nscloud-ubuntu-20.04-amd64-8x8-with-cache
-      - nscloud-cache-tag-obscuravpn-api
-      - nscloud-cache-size-20gb
+    runs-on: [nix]
     steps:
       - name: git checkout
         uses: actions/checkout@v4
 
-      - uses: namespacelabs/nscloud-cache-action@v1
-        with:
-          path: /nix
-
-      - name: Install Nix
-        uses: cachix/install-nix-action@v31
-
       - name: Build Nix
         shell: bash
         run: |
           nix flake check \
-            --experimental-features "flakes nix-command" \
             --keep-going \
             --no-update-lock-file \
             --print-build-logs \