Merge pull request #1979 from mybatis/dependabot/maven/mysql-mysql-connector-java-8.0.21

Bump mysql-connector-java from 8.0.20 to 8.0.21

Author: hazendaz

pom.xml

@@ -249,7 +249,7 @@
     <dependency>
       <groupId>mysql</groupId>
       <artifactId>mysql-connector-java</artifactId>
-      <version>8.0.20</version>
+      <version>8.0.21</version>
       <scope>test</scope>
     </dependency>
     <dependency>