chore: migrate GitHub Actions workflows to ubuntu-slim runners (#67)

* Initial plan

* chore: replace ubuntu-latest with ubuntu-slim in all workflows

Co-authored-by: nicolasleger <570901+nicolasleger@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: nicolasleger <570901+nicolasleger@users.noreply.github.com>

Author: Copilot

.github/workflows/auto-assign-pr.yml

@@ -10,6 +10,6 @@ permissions:
 
 jobs:
   assign-author:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: toshimaru/auto-author-assign@v2.1.1

.github/workflows/github-projects.yml

@@ -14,7 +14,7 @@ permissions:
 jobs:
   add-to-design-project:
     name: 🎨 Add issue to the openfoodfacts-design project
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: actions/add-to-project@main
         with:

.github/workflows/publish.yml

@@ -11,7 +11,7 @@ permissions:
 
 jobs:
   publish:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     environment: release
     steps:
       - uses: actions/checkout@v5

.github/workflows/release-please.yml

@@ -12,7 +12,7 @@ permissions:
 
 jobs:
   release-please:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: GoogleCloudPlatform/release-please-action@v4
         id: release

.github/workflows/rubocop-analysis.yml

@@ -8,7 +8,7 @@ permissions:
 
 jobs:
   rubocop:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     strategy:
       fail-fast: false
 

.github/workflows/ruby.yml

@@ -12,7 +12,7 @@ permissions:
 jobs:
   test:
 
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     strategy:
       fail-fast: false
       matrix:

.github/workflows/semantic-pr.yml

@@ -13,7 +13,7 @@ permissions:
 jobs:
   main:
     name: Validate PR title
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-slim
     steps:
       - uses: amannn/action-semantic-pull-request@v6
         env: