Bump for 1.28

Author: nicolas-grekas

composer.json

@@ -31,7 +31,7 @@
     "minimum-stability": "dev",
     "extra": {
         "branch-alias": {
-            "dev-main": "1.27-dev"
+            "dev-main": "1.28-dev"
         },
         "thanks": {
             "name": "symfony/polyfill",