Use ubuntu-latest for all workflows

There's generally no point running on multiple versions as
the important things like ruby are note the OS versions in any
case and production runs on Debian now not Ubuntu.

.github/workflows/danger.yml

@@ -10,7 +10,7 @@ permissions:
 
 jobs:
   danger:
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     steps:
       - name: Check out code
         uses: actions/checkout@v4

.github/workflows/docker.yml

@@ -8,7 +8,7 @@ concurrency:
 jobs:
   test:
     name: Docker
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     steps:
     - name: Checkout source
       uses: actions/checkout@v4

.github/workflows/lint.yml

@@ -6,12 +6,11 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.head_ref || github.ref }}
   cancel-in-progress: true
 env:
-  os: ubuntu-22.04
   ruby: '3.1'
 jobs:
   rubocop:
     name: RuboCop
-    runs-on: ubuntu-22.04
+    runs-on: ubuntu-latest
     steps:
     - name: Check out code
       uses: actions/checkout@v4

.github/workflows/tests.yml

@@ -7,12 +7,11 @@ concurrency:
   cancel-in-progress: true
 jobs:
   test:
-    name: Ubuntu ${{ matrix.ubuntu }}, Ruby ${{ matrix.ruby }}
+    name: Ruby ${{ matrix.ruby }}
     strategy:
       matrix:
-        ubuntu: [22.04, 24.04]
         ruby: ['3.1', '3.2', '3.3', '3.4']
-    runs-on: ubuntu-${{ matrix.ubuntu }}
+    runs-on: ubuntu-latest
     env:
       RAILS_ENV: test
       OPENSTREETMAP_MEMCACHE_SERVERS: 127.0.0.1
@@ -65,7 +64,7 @@ jobs:
       uses: coverallsapp/github-action@v2.3.6
       with:
         github-token: ${{ secrets.github_token }}
-        flag-name: ubuntu-${{ matrix.ubuntu }}-ruby-${{ matrix.ruby }}
+        flag-name: ruby-${{ matrix.ruby }}
         format: lcov
         parallel: true
   finish: