twrp version update: update to 3.4.0 release notes are on twrp.me

Change-Id: I3762fb3e2c3ffb4cbdc6d93ce424cacc7e0ef418
(cherry picked from commit e0e43403b9bdd9261e733aa0448d7689a9f23ced)
diff --git a/variables.h b/variables.h
index 24cde92..32a7b99 100644
--- a/variables.h
+++ b/variables.h
@@ -17,7 +17,7 @@
 #ifndef _VARIABLES_HEADER_
 #define _VARIABLES_HEADER_
 
-#define TW_MAIN_VERSION_STR       "3.3.1"
+#define TW_MAIN_VERSION_STR       "3.4.0"
 #define TW_VERSION_STR TW_MAIN_VERSION_STR TW_DEVICE_VERSION
 
 #define TW_USE_COMPRESSION_VAR      "tw_use_compression"