chore: add renovate config with SHA-pinned action regex manager, fix gitlabci image quotes

.gitea/workflows/docker-build.yaml

@@ -3,7 +3,6 @@ name: Docker Build and Push
 on:
   pull_request:
   push:
-    branches: [master]
   schedule:
     - cron: '30 3 * * 3'
 

.gitlab-ci.yml

@@ -1,4 +1,4 @@
-image: "docker:latest"
+image: docker:latest
 
 services:
   - "docker:dind"

Dockerfile

@@ -1,4 +1,4 @@
-FROM ubuntu:26.04
+FROM ubuntu:18.04
 LABEL maintainer="Julien Cabillot <dockerimages@cabillot.eu>"
 
 ENV DEBIAN_FRONTEND=noninteractive

renovate.json

@@ -0,0 +1,17 @@
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "gitlabci": {
+    "enabled": true
+  },
+  "regexManagers": [
+    {
+      "description": "Track SHA-pinned Gitea Actions (github-actions manager on Gitea platform cannot resolve SHA refs natively)",
+      "fileMatch": ["^\\.gitea/workflows/.*\\.ya?ml$"],
+      "matchStrings": [
+        "uses:\\s+(?<depName>[\\w.-]+\\/[\\w.-]+(?:\\/[\\w.-]+)?)@(?<currentDigest>[a-f0-9]{40})"
+      ],
+      "datasourceTemplate": "github-releases",
+      "versioningTemplate": "semver"
+    }
+  ]
+}