[CI/chore] Update workflows to run on ubuntu-latest

... rather than `ubuntu-2x.xx`

Author: chalin

.github/workflows/auto-update-community-members.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   auto-update-versions:
     name: Auto-update community members page
-    runs-on: ubuntu-24.04
+    runs-on: ubuntu-latest
     # Remove the if statement below when testing against a fork
     if: github.repository == 'open-telemetry/opentelemetry.io'
     steps:

.github/workflows/auto-update-registry.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   auto-update-versions:
     name: Auto-update registry versions
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     # Remove the if statement below when testing against a fork
     if: github.repository == 'open-telemetry/opentelemetry.io'
     steps:

.github/workflows/auto-update-versions.yml

@@ -9,7 +9,7 @@ on:
 jobs:
   auto-update-versions:
     name: Auto-update versions
-    runs-on: ubuntu-20.04
+    runs-on: ubuntu-latest
     if: github.repository == 'open-telemetry/opentelemetry.io'
     env:
       DEPTH: --depth 999 # submodule clone depth