Update SQLServer DDL script to use VARCHAR instead of TEXT

The TEXT datatype has been deprecated since SQLServer 2017.

This commit updates the script to use the suggested
replacement, which is VARCHAR(MAX).

Resolves #864

Author: fmbenhassine

spring-batch-core/src/main/resources/org/springframework/batch/core/schema-sqlserver.sql

@@ -63,15 +63,15 @@ CREATE TABLE BATCH_STEP_EXECUTION  (
 CREATE TABLE BATCH_STEP_EXECUTION_CONTEXT  (
 	STEP_EXECUTION_ID BIGINT NOT NULL PRIMARY KEY,
 	SHORT_CONTEXT VARCHAR(2500) NOT NULL,
-	SERIALIZED_CONTEXT TEXT NULL,
+	SERIALIZED_CONTEXT VARCHAR(MAX) NULL,
 	constraint STEP_EXEC_CTX_FK foreign key (STEP_EXECUTION_ID)
 	references BATCH_STEP_EXECUTION(STEP_EXECUTION_ID)
 ) ;
 
 CREATE TABLE BATCH_JOB_EXECUTION_CONTEXT  (
 	JOB_EXECUTION_ID BIGINT NOT NULL PRIMARY KEY,
 	SHORT_CONTEXT VARCHAR(2500) NOT NULL,
-	SERIALIZED_CONTEXT TEXT NULL,
+	SERIALIZED_CONTEXT VARCHAR(MAX) NULL,
 	constraint JOB_EXEC_CTX_FK foreign key (JOB_EXECUTION_ID)
 	references BATCH_JOB_EXECUTION(JOB_EXECUTION_ID)
 ) ;