Call URI.open directly

[laurentqro]

Removes warning: "calling URI.open via Kernel#open is deprecated, call URI.open directly or use URI#open"

[ekohl]

Looks like this breaks Ruby 2.4 support. Perhaps we should modify this to 2.5+

json-schema/json-schema.gemspec

Line 17 in 450489b

s.required_ruby_version = ">= 1.9"

[codecov]

Codecov Report

Merging #459 (d895570) into master (450489b) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #459   +/-   ##
=======================================
  Coverage   89.75%   89.75%           
=======================================
  Files          74       74           
  Lines        1581     1581           
=======================================
  Hits         1419     1419           
  Misses        162      162           

Impacted Files	Coverage Δ
lib/json-schema/schema/reader.rb	98.07% <100.00%> (ø)
lib/json-schema/validator.rb	84.59% <100.00%> (ø)

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[bastelfreak]

thanks for the PR, merged it in #462