Merge pull request nextcloud#12381 from nextcloud/bump328

bump to 3.28.0 alpha

Author: tobiasKaminsky

app/build.gradle

@@ -60,7 +60,7 @@ configurations.configureEach {
 
 // semantic versioning for version code
 def versionMajor = 3
-def versionMinor = 27
+def versionMinor = 28
 def versionPatch = 0
 def versionBuild = 0 // 0-50=Alpha / 51-98=RC / 90-99=stable