Update openresty runner

Author: rechner

.github/workflows/test_openresty.yml

@@ -12,7 +12,7 @@ jobs:
        matrix:
          version: [1.21.4.3, 1.25.3.1]
        fail-fast: false
-    runs-on: "ubuntu-20.04"
+    runs-on: "ubuntu-24.04"
 
     steps:
     - uses: actions/checkout@v3