try travis for latest ruby version

.travis.yml

@@ -3,7 +3,8 @@ language: ruby
 rvm:
   - 2.3.4
   - 2.4.1
-  - 2.5.3
+  - 2.5.6
+  - 2.6.5
 before_install:
   - gem uninstall -v '>= 2' -i $(rvm gemdir)@global -ax bundler || true
   - gem install bundler -v '< 2'

lib/cryptoexchange/helpers/numeric_helper.rb

@@ -3,7 +3,7 @@ class << self
     def to_d(number)
       if !number.nil? || number != ""
         num = number.to_s
-        num.empty? ? nil : BigDecimal.new(num)
+        num.empty? ? nil : BigDecimal(num)
       else
         nil
       end
@@ -19,7 +19,7 @@ def divide(number, divisor)
     end
 
     def to_numeric(number)
-      result = BigDecimal.new(number.to_s)
+      result = BigDecimal(number.to_s)
       if result.frac.zero?
         result.to_i
       else