github: set branch to 5.8 [skip ci]

.devcontainer/devcontainer.json

@@ -4,7 +4,7 @@
    */
   "name": "Debian",
   "build": {
-    "cacheFrom": "ghcr.io/kamailio/kamailio-master-devcontainer",
+    "cacheFrom": "ghcr.io/kamailio/kamailio-5.8-devcontainer",
     "context": "../pkg/kamailio/deb",
     "dockerfile": "Dockerfile"
   },

.github/workflows/devcontainer.yaml

@@ -4,7 +4,7 @@ name: build devcontainer image
 'on':
   push:
     branches:
-      - master
+      - 5.8
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
     inputs:

.github/workflows/main.yml

@@ -3,7 +3,7 @@ name: build
 'on':
   push:
     branches:
-      - master
+      - 5.8
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
 jobs: