Revert "Upgrade to Saaj Impl 1.5.1"

This reverts commit 1f47bd9.

See gh-15915

Author: wilkinsona

spring-boot-project/spring-boot-dependencies/pom.xml

@@ -181,7 +181,7 @@
 		<sqlite-jdbc.version>3.25.2</sqlite-jdbc.version>
 		<statsd-client.version>3.1.0</statsd-client.version>
 		<sun-mail.version>${javax-mail.version}</sun-mail.version>
-		<saaj-impl.version>1.5.1</saaj-impl.version>
+		<saaj-impl.version>1.5.0</saaj-impl.version>
 		<thymeleaf.version>3.0.11.RELEASE</thymeleaf.version>
 		<thymeleaf-extras-springsecurity.version>3.0.4.RELEASE</thymeleaf-extras-springsecurity.version>
 		<thymeleaf-layout-dialect.version>2.3.0</thymeleaf-layout-dialect.version>