Remove backward compatible code

Author: wpolicarpo

lib/active_record/connection_adapters/sqlserver/schema_creation.rb

@@ -3,11 +3,7 @@
 module ActiveRecord
   module ConnectionAdapters
     module SQLServer
-      BASE_SCHEMA_CREATION_CLASS = Rails::VERSION::MAJOR >= 6 && Rails::VERSION::MINOR >= 1 ?
-        SchemaCreation :
-        AbstractAdapter::SchemaCreation
-
-      class SchemaCreation < BASE_SCHEMA_CREATION_CLASS
+      class SchemaCreation < SchemaCreation
         private
 
         def visit_TableDefinition(o)

lib/active_record/connection_adapters/sqlserver/transaction.rb

@@ -31,18 +31,10 @@ def current_isolation_level
     module SQLServerRealTransaction
       attr_reader :starting_isolation_level
 
-      if Rails::VERSION::MAJOR >= 6 && Rails::VERSION::MINOR >= 1
-        def initialize(connection, **args)
-          @connection = connection
-          @starting_isolation_level = current_isolation_level if args[:isolation]
-          super
-        end
-      else
-        def initialize(connection, options, **args)
-          @connection = connection
-          @starting_isolation_level = current_isolation_level if options[:isolation]
-          super
-        end
+      def initialize(connection, isolation: nil, joinable: true, run_commit_callbacks: false)
+        @connection = connection
+        @starting_isolation_level = current_isolation_level if isolation
+        super
       end
 
       def commit