revert: build(pom.xml): update mysql-connector-java to 5.1.47

This reverts commit 21e3a7a.

It's turned out that the new version causes NullPointerException. See
https://bugs.mysql.com/bug.php?id=92089 for details.

Author: php-coder

Diff for: pom.xml

@@ -548,7 +548,7 @@
 		<minify.plugin.version>1.7.6</minify.plugin.version>
 
 		<!-- Redefine default value from spring-boot-dependencies (https://github.com/spring-projects/spring-boot/blob/v1.5.16.RELEASE/spring-boot-dependencies/pom.xml) -->
-		<mysql.version>5.1.47</mysql.version>
+		<mysql.version>5.1.46</mysql.version>
 
 		<native2ascii.plugin.version>2.0.1</native2ascii.plugin.version>
 		<owasp-plugin.version>3.0.2</owasp-plugin.version>