Fix Tagged Logging when using Rails 6 (#8)

* Use local variable to support Rails 6

* Bump gem version

Author: simonrozsival

lib/logtail/logger.rb

@@ -55,7 +55,8 @@ def build_log_entry(severity, time, progname, logged_obj)
 
         # Because of all the crazy ways Rails has attempted tags, we need this crazy method.
         def extract_active_support_tagged_logging_tags
-          Thread.current[:activesupport_tagged_logging_tags] ||
+          @current_tags ||
+            Thread.current[:activesupport_tagged_logging_tags] ||
             Thread.current[tagged_logging_object_key_name] ||
             EMPTY_ARRAY
         end

lib/logtail/version.rb

@@ -1,3 +1,3 @@
 module Logtail
-  VERSION = "0.1.4"
+  VERSION = "0.1.5"
 end