update renovate rules with new LTS versions

- remove old Django lts version and add new one
- remove old wagtail lts versions

renovate.json

@@ -27,11 +27,11 @@
       },
       {
         "matchPackageNames": ["Django"],
-        "allowedVersions": "/(^3\\.2\\.[0-9]+$)|(^4\\.2\\.[0-9]+$)|(^5\\.2\\.[0-9]+$)/"
+        "allowedVersions": "/(^4\\.2\\.[0-9]+$)|(^5\\.2\\.[0-9]+$)|(^6\\.2\\.[0-9]+$)/"
       },
       {
         "matchPackageNames": ["wagtail"],
-        "allowedVersions": "/(^4\\.1(\\.[0-9]+)?$)|(^5\\.2(\\.[0-9]+)?$)/"
+        "allowedVersions": "/(^6\\.3(\\.[0-9]+)?$)/"
       },
       {
         "matchPackageNames": ["bootstrap"],