[ruby/time] Bump up time version to 0.2.0

https://github.com/ruby/time/commit/b9dd593b23
2021-10-14 20:42:13 +09:00 · 2021-10-14 20:42:13 +09:00 · e6b3eab1b7
--- a/lib/time.gemspec
+++ b/lib/time.gemspec
@ -1,6 +1,6 @@
 Gem::Specification.new do |spec|
  spec.name          = "time"
-  spec.version       = "0.1.0"
+  spec.version       = "0.2.0"
  spec.authors       = ["Tanaka Akira"]
  spec.email         = ["akr@fsij.org"]