Bump app version on master to 3.24

Signed-off-by: Álvaro Brey <alvaro.brey@nextcloud.com>

app/build.gradle

@@ -58,7 +58,7 @@ configurations.configureEach {
 
 // semantic versioning for version code
 def versionMajor = 3
-def versionMinor = 23
+def versionMinor = 24
 def versionPatch = 0
 def versionBuild = 0 // 0-50=Alpha / 51-98=RC / 90-99=stable