ci: use Warp runners for all workflows

Switch from GitHub-hosted ubuntu-latest to warp-ubuntu-latest-arm64-2x
to avoid consuming GitHub Actions minutes.

Author: typedrat

.github/workflows/ci.yml

@@ -10,7 +10,7 @@ permissions:
 
 jobs:
   validate:
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-arm64-2x
     steps:
       - uses: actions/checkout@v4
       - uses: DeterminateSystems/determinate-nix-action@v3

.github/workflows/publish-flakehub.yml

@@ -15,7 +15,7 @@ permissions:
 
 jobs:
   publish:
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-arm64-2x
     steps:
       - uses: actions/checkout@v4
         with:

.github/workflows/update-flake-lock.yml

@@ -11,7 +11,7 @@ permissions:
 
 jobs:
   update:
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-arm64-2x
     steps:
       - uses: actions/checkout@v4
       - name: Set git identity

.github/workflows/update-versions.yml

@@ -14,7 +14,7 @@ permissions:
 
 jobs:
   update:
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-arm64-2x
     steps:
       - uses: actions/checkout@v4
         with:
@@ -43,7 +43,7 @@ jobs:
 
   prune:
     needs: update
-    runs-on: ubuntu-latest
+    runs-on: warp-ubuntu-latest-arm64-2x
     steps:
       - uses: actions/checkout@v4
       - uses: DeterminateSystems/determinate-nix-action@v3