feat: use deep_merge instead of merge for hash val

lib/tallty_import_export/import.rb

@@ -158,7 +158,7 @@ module TalltyImportExport
           attr = k_arr.first
           val = { k_arr[1..-1].join('.') => v }.to_nested_hash
           h[attr.to_sym] ||= {}
-          h[attr.to_sym].merge! val
+          h[attr.to_sym].deep_merge! val
         else
           h[k.to_sym] = val
         end

lib/tallty_import_export/version.rb

 module TalltyImportExport
-  VERSION = '1.1.5'
+  VERSION = '1.1.6'
 end