Upgrade to Slf4j 1.7.29

Closes spring-projectsgh-18863

Author: wilkinsona

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

@@ -182,7 +182,7 @@
 		<selenium-htmlunit.version>2.36.0</selenium-htmlunit.version>
 		<sendgrid.version>4.4.1</sendgrid.version>
 		<servlet-api.version>4.0.1</servlet-api.version>
-		<slf4j.version>1.7.28</slf4j.version>
+		<slf4j.version>1.7.29</slf4j.version>
 		<snakeyaml.version>1.25</snakeyaml.version>
 		<solr.version>8.2.0</solr.version>
 		<spring-amqp.version>2.2.1.BUILD-SNAPSHOT</spring-amqp.version>