Merge branch '5.1' into 5.x

* 5.1:
  [Contracts] add branch-aliases for dev-main
  [Cache] Make Redis initializers static
  [Messenger] Fixed typos in Connection
  [CI] Fixed build on AppVeyor
  Fix tests typo
  [Lock] Reset Key lifetime time before we acquire it
  [CI] Silence errors when remove file/dir on test tearDown()
  Fix tests
  Remove content-type check on toArray methods

Author: nicolas-grekas

composer.json

@@ -26,12 +26,13 @@
     },
     "minimum-stability": "dev",
     "extra": {
+        "branch-version": "2.3",
+        "branch-alias": {
+            "dev-main": "2.3-dev"
+        },
         "thanks": {
             "name": "symfony/contracts",
             "url": "https://github.com/symfony/contracts"
         }
-    },
-    "extra": {
-        "branch-version": "2.3"
     }
 }