Fix ruby_version guards in Unicode/Emoji version specs

Correct version guards in ruby_version in Unicode/Emoji version
specs to correctly use exclusive range endings.

Author: duerst

library/rbconfig/unicode_emoji_version_spec.rb

@@ -14,8 +14,8 @@
     end
   end
 
-  ruby_version_is "2.7"..."3.0" do
-    it "is 12.1 for Ruby 2.7" do
+  ruby_version_is "2.7"..."3.1" do
+    it "is 12.1 for Ruby 2.7 and 3.0" do
       RbConfig::CONFIG['UNICODE_EMOJI_VERSION'].should == "12.1"
     end
   end

library/rbconfig/unicode_version_spec.rb

@@ -20,7 +20,7 @@
     end
   end
 
-  ruby_version_is "2.6.3"..."3.0" do
+  ruby_version_is "2.6.3"..."3.1" do
     it "is 12.1.0 for Ruby 2.6.3+, Ruby 2.7, and Ruby 3.0" do
       RbConfig::CONFIG['UNICODE_VERSION'].should == "12.1.0"
     end