ci: use slim Ubuntu runners

It will be more environmentally friendly and cheaper

GitHub blog post about new 1 vCPU runners: https://github.blog/changelog/2025-10-28-1-vcpu-linux-runner-now-available-in-github-actions-in-public-preview

Pricing (tl;dr: /bin/bash.002/min): https://docs.github.com/en/billing/reference/actions-runner-pricing

GitHub-hosted runners reference: https://docs.github.com/en/actions/reference/workflows-and-actions/workflow-syntax#standard-github-hosted-runners-for--private-repositories

Author: okineadev

.github/workflows/provenance.yml

@@ -14,7 +14,7 @@ permissions:
   contents: read
 jobs:
   check-provenance:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: actions/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8 # v6.0.1
         with:

.github/workflows/semantic-pull-requests.yml

@@ -16,7 +16,7 @@ jobs:
       pull-requests: read # for amannn/action-semantic-pull-request to analyze PRs
       statuses: write # for amannn/action-semantic-pull-request to mark status of analyzed PR
     if: github.repository == 'npmx-dev/npmx.dev'
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     name: semantic-pr
     steps:
       - name: Validate PR title