Update core to 10.3.7. DDFNEXT-396

We're pinning the version specifically to 10.3.7, rather
than running `composer update`. We do this, both because
we prefer it this way, but also because we have a problem
when running update, that for some reason, the DPL setup
wants to enable a dev version of Drupal core.
We're not sure why, but, for now, it does not matter, as we
are pinning.

composer.json

@@ -110,9 +110,9 @@
         "drupal/consumers": "^1.19",
         "drupal/content_lock": "^2.3",
         "drupal/cookieinformation": "^2.1",
-        "drupal/core-composer-scaffold": "^10.3",
-        "drupal/core-project-message": "^10.3",
-        "drupal/core-recommended": "^10.3",
+        "drupal/core-composer-scaffold": "10.3.7",
+        "drupal/core-project-message": "10.3.7",
+        "drupal/core-recommended": "10.3.7",
         "drupal/date_range_formatter": "^4.0",
         "drupal/default_content": "^2.0@alpha",
         "drupal/devel": "^5.1",