Switch to latest CI runner image

Author: jmattsson

.github/workflows/build.yml

@@ -12,7 +12,7 @@ jobs:
         numbers: ['default', 'alternate']
         target: ['esp32', 'esp32s2', 'esp32s3', 'esp32c3', 'esp32c6', 'esp32h2']
 
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
 
     steps:
       - uses: actions/checkout@v4