[CI] Updates GitHub Actions 8.19

Author: picandocodigo

.github/workflows/8.x.yml renamed to .github/workflows/8.19.yml

@@ -2,10 +2,10 @@ name: opentelemetry
 on:
   push:
     branches:
-      - 8.x
+      - 8.19
   pull_request:
     branches:
-      - 8.x
+      - 8.19
 jobs:
   test-otel:
     name: 'Test Open Telemetry'