Fix publish flow file name (#151)

Author: Barry-Zou

.github/workflows/publish.yml

@@ -40,4 +40,4 @@ jobs:
         run: |
           gem build square.gemspec
 
-          gem push square-*.gem --host https://rubygems.org/
+          gem push square.rb-*.gem --host https://rubygems.org/

README.md

@@ -20,7 +20,7 @@ Use this library to integrate Square payments into your app and grow your busine
 
 Use of the Square Ruby SDK requires:
 
-* Ruby 2.6 through 3.1
+* Ruby 2.7 through 3.1
 
 ## Installation