Remove obsolete ruby-oci8 2.0.3 patches and require 2.1.0+

- Remove oci8_patches.rb which patched TIMESTAMP fractional seconds
  for ruby-oci8 2.0.3
- Bump minimum ruby-oci8 version from 2.0.3 to 2.1.0
- Use Gem::Version for version comparison
- Update README to reflect current requirements

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yahonda

README.md

@@ -135,7 +135,7 @@ or include gem in Gemfile if using bundler.
 
 In addition install either ruby-oci8 (for MRI/YARV) or copy Oracle JDBC driver to $JRUBY_HOME/lib (for JRuby).
 
-If you are using MRI Ruby implementation then you need to install ruby-oci8 gem (version 2.0.x or 2.1.x)
+If you are using MRI Ruby implementation then you need to install ruby-oci8 gem (version 2.1 or higher)
 as well as Oracle client, e.g. [Oracle Instant Client](http://www.oracle.com/technetwork/database/features/instant-client/index-097480.html).
 
 If you are using JRuby then you need to download latest [Oracle JDBC driver](http://www.oracle.com/technetwork/database/enterprise-edition/jdbc-112010-090769.html) - either ojdbc7.jar for Java 8 and 7, ojdbc6.jar for Java 6, 7, 8 or ojdbc5.jar for Java 5. You can refer [the support matrix](http://www.oracle.com/technetwork/database/enterprise-edition/jdbc-faq-090281.html#01_03) for details.

lib/plsql/oci8_patches.rb

@@ -14,13 +14,9 @@
   raise LoadError, "ERROR: ruby-plsql could not load ruby-oci8 library. #{msg}"
 end
 
-require "plsql/oci8_patches"
-
 # check ruby-oci8 version
-required_oci8_version = [2, 0, 3]
-oci8_version_ints = OCI8::VERSION.scan(/\d+/).map { |s| s.to_i }
-if (oci8_version_ints <=> required_oci8_version) < 0
-  raise LoadError, "ERROR: ruby-oci8 version #{OCI8::VERSION} is too old. Please install ruby-oci8 version #{required_oci8_version.join('.')} or later."
+if Gem::Version.new(OCI8::VERSION) < Gem::Version.new("2.1.0")
+  raise LoadError, "ERROR: ruby-oci8 version #{OCI8::VERSION} is too old. Please install ruby-oci8 version 2.1.0 or later."
 end
 
 module PLSQL