Update runners to ubuntu-24.04 from deprecated ubuntu-20.04 label (#2143)

Co-authored-by: Bill Napier <napier@google.com>

Author: google-admin

.github/workflows/api.yml

@@ -58,7 +58,7 @@ jobs:
   linux:
     if: github.repository == 'tensorflow/io' # Don't do this in forks
     name: Linux ${{ matrix.python }} + ${{ matrix.version }}
-    runs-on: ubuntu-20.04
+    runs-on: 'ubuntu-24.04'
     strategy:
       fail-fast: false
       matrix: