Add bin and edit workflow

bin/gems/bigdecimal-3.1.9/bigdecimal.gemspec

@@ -0,0 +1,57 @@
+# coding: utf-8
+
+name = File.basename(__FILE__, '.*')
+source_version = ["", "ext/#{name}/"].find do |dir|
+  begin
+    break File.foreach(File.join(__dir__, "#{dir}#{name}.c")) {|line|
+      break $1.sub("-", ".") if /^#define\s+#{name.upcase}_VERSION\s+"(.+)"/o =~ line
+    }
+  rescue Errno::ENOENT
+  end
+end or raise "can't find #{name.upcase}_VERSION"
+
+Gem::Specification.new do |s|
+  s.name          = name
+  s.version       = source_version
+  s.authors       = ["Kenta Murata", "Zachary Scott", "Shigeo Kobayashi"]
+  s.email         = ["mrkn@mrkn.jp"]
+
+  s.summary       = "Arbitrary-precision decimal floating-point number library."
+  s.description   = "This library provides arbitrary-precision decimal floating-point number class."
+  s.homepage      = "https://github.com/ruby/bigdecimal"
+  s.licenses       = ["Ruby", "BSD-2-Clause"]
+
+  s.require_paths = %w[lib]
+  s.files         = %w[
+    LICENSE
+    bigdecimal.gemspec
+    lib/bigdecimal.rb
+    lib/bigdecimal/jacobian.rb
+    lib/bigdecimal/ludcmp.rb
+    lib/bigdecimal/math.rb
+    lib/bigdecimal/newton.rb
+    lib/bigdecimal/util.rb
+    sample/linear.rb
+    sample/nlsolve.rb
+    sample/pi.rb
+  ]
+  if Gem::Platform === s.platform and s.platform =~ 'java' or RUBY_ENGINE == 'jruby'
+    s.platform      = 'java'
+  else
+    s.extensions    = %w[ext/bigdecimal/extconf.rb]
+    s.files += %w[
+      ext/bigdecimal/bigdecimal.c
+      ext/bigdecimal/bigdecimal.h
+      ext/bigdecimal/bits.h
+      ext/bigdecimal/feature.h
+      ext/bigdecimal/missing.c
+      ext/bigdecimal/missing.h
+      ext/bigdecimal/missing/dtoa.c
+      ext/bigdecimal/static_assert.h
+    ]
+  end
+
+  s.required_ruby_version = Gem::Requirement.new(">= 2.5.0")
+
+  s.metadata["changelog_uri"] = s.homepage + "/blob/master/CHANGES.md"
+end