MNT Revert erroneous dependency changes (#10739)

Author: GuySartorelli

composer.json

@@ -33,8 +33,8 @@
         "monolog/monolog": "^1.16",
         "nikic/php-parser": "^4.10.5",
         "psr/container": "^1",
-        "silverstripe/config": "1.6.x-dev",
-        "silverstripe/assets": "1.13.x-dev",
+        "silverstripe/config": "^1@dev",
+        "silverstripe/assets": "^1@dev",
         "silverstripe/vendor-plugin": "^1.6",
         "sminnee/callbacklist": "^0.1",
         "swiftmailer/swiftmailer": "^6.2",