Update runners to ubuntu-24.04 from deprecated ubuntu-20.04 label

Author: billnapier

.github/workflows/ci.yml

@@ -48,13 +48,13 @@ jobs:
         # We support an optional key: args, for cmake args
         include:
           # Just add a key
-          - runs-on: ubuntu-20.04
+          - runs-on: 'ubuntu-24.04'
             python: '3.8'
             args: >
               -DPYBIND11_FINDPYTHON=ON
               -DCMAKE_CXX_FLAGS="-D_=1"
             exercise_D_: 1
-          - runs-on: ubuntu-20.04
+          - runs-on: 'ubuntu-24.04'
             python: 'pypy-3.8'
             args: >
               -DPYBIND11_FINDPYTHON=ON
@@ -249,7 +249,7 @@ jobs:
           python-debug: false
 
     name: "🐍 ${{ matrix.python-version }}${{ matrix.python-debug && '-dbg' || '' }} (deadsnakes)${{ matrix.valgrind && ' • Valgrind' || '' }} • x64"
-    runs-on: ubuntu-20.04
+    runs-on: 'ubuntu-24.04'
 
     steps:
     - uses: actions/checkout@v4
@@ -452,7 +452,7 @@ jobs:
 
   # Testing on Ubuntu + NVHPC (previous PGI) compilers, which seems to require more workarounds
   ubuntu-nvhpc7:
-    runs-on: ubuntu-20.04
+    runs-on: 'ubuntu-24.04'
     name: "🐍 3 • NVHPC 23.5 • C++17 • x64"
 
     env:
@@ -572,7 +572,7 @@ jobs:
 
   # Testing on ICC using the oneAPI apt repo
   icc:
-    runs-on: ubuntu-20.04
+    runs-on: 'ubuntu-24.04'
 
     name: "🐍 3 • ICC latest • x64"