define database::kCurrentDbVersion publicly

src/database/database.cpp

@@ -56,7 +56,6 @@ static SingletonEnv<leveldb::EspEnv> sEnv;
 static const char kDbPath[] = "/.tangara-db";
 
 static const char kKeyDbVersion[] = "schema_version";
-static const uint8_t kCurrentDbVersion = 5;
 
 static const char kKeyCustom[] = "U\0";
 static const char kKeyCollator[] = "collator";

src/database/include/database.hpp

@@ -35,6 +35,8 @@
 
 namespace database {
 
+const uint8_t kCurrentDbVersion = 5;
+
 struct SearchKey;
 class Record;
 class Iterator;