Merge branch '5.2' into 5.3

* 5.2:
  Fix incompatible implicit float-to-int conversions
  [Translation] Don't pass null to strtoupper()
  cs fix
  [String] Fix implicit float-to-int casts
  [DependencyInjection] Don't pass null to trim()
  Add return types to JsonSerializable implementations
  Fix Serializable deprecations triggered by token mocks
  Add missing security translations

Author: derrabus

Tests/Store/PdoStoreTest.php

@@ -72,7 +72,7 @@ public function testInvalidTtlConstruct()
     {
         $this->expectException(InvalidTtlException::class);
 
-        return new PdoStore('sqlite:'.self::$dbFile, [], 0.1, 0.1);
+        return new PdoStore('sqlite:'.self::$dbFile, [], 0.1, 0);
     }
 
     /**