Resolve "Investigate renovate not finding remote repository"

See merge request !550

Co-authored-by: Neil-Jocelyn Schark <--global>
Co-authored-by: Neil Schark <gitlab@schark.eu>

.gitlab/ci/.renovate.yml

 renovate:
     stage: tools
 
-    image: renovate/renovate:36.93.6
+    image: renovate/renovate:37.6.1
 
     variables:
         LOG_LEVEL: debug

config.js

@@ -21,5 +21,5 @@ module.exports = {
   prConcurrentLimit: 10,
   commitMessagePrefix: '[renovate]',
   labels: ['renovate'],
-  baseBranches: ['mainline']
+  baseBranches: ['master']
 };

renovate.json

 {
     "$schema": "https://docs.renovatebot.com/renovate-schema.json",
     "gitAuthor": "renovate@danet.fbi.h-da.de",
+    "platform": "gitlab",
     "ignorePaths": [
         "**/node_modules/**",
         "**/bower_components/**",