bump wp tested-up-to version 5.7 in trunk

matches version set on `develop`

Author: jeffpaul

readme.txt

@@ -2,7 +2,7 @@
 Contributors:      10up, helen, welcher, fabiankaegy, dinhtungdu
 Tags:              apple maps, map block, block
 Requires at least: 5.2
-Tested up to:      5.5
+Tested up to:      5.7
 Requires PHP:      5.6
 Stable tag:        1.0.1
 License:           GPLv2 or later