ci: run linux jobs on lux-build-amd64 ARC scale set (no GitHub-hosted builders)

.github/workflows/build.yml

@@ -9,7 +9,7 @@ permissions:
 jobs:
   build:
     name: Build binaries
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     strategy:
       matrix:
         include:
@@ -68,7 +68,7 @@ jobs:
           path: age-*
   source:
     name: Package source code
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - name: Checkout repository
         uses: actions/checkout@v5
@@ -106,7 +106,7 @@ jobs:
       contents: write
       attestations: write
       id-token: write
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - name: Download workflow artifacts
         uses: actions/download-artifact@v4

.github/workflows/interop.yml

@@ -5,7 +5,7 @@ permissions:
 jobs:
   trigger:
     name: Trigger
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - name: Trigger interoperability tests in str4d/rage
         continue-on-error: true

.github/workflows/ronn.yml

@@ -11,7 +11,7 @@ permissions:
 jobs:
   ronn:
     name: Ronn
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - uses: actions/checkout@v5
         with:
@@ -40,7 +40,7 @@ jobs:
     needs: ronn
     permissions:
       contents: write
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - uses: actions/checkout@v5
         with:

.github/workflows/test.yml

@@ -30,7 +30,7 @@ jobs:
       - run: |
           go test -race ./...
   test-latest:
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     strategy:
       fail-fast: false
       matrix:
@@ -50,7 +50,7 @@ jobs:
             go get -u -t ./...
             go test -race ./...
   staticcheck:
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - uses: actions/checkout@v5
         with:
@@ -62,7 +62,7 @@ jobs:
         with:
           run: go run honnef.co/go/tools/cmd/staticcheck@latest ./...
   govulncheck:
-    runs-on: ubuntu-latest
+    runs-on: lux-build-amd64
     steps:
       - uses: actions/checkout@v5
         with: