Bump socket-factory.version from 1.18.0 to 1.21.0

Bumps `socket-factory.version` from 1.18.0 to 1.21.0.

Updates `com.google.cloud.sql:postgres-socket-factory` from 1.18.0 to 1.21.0

Updates `com.google.cloud.sql:mysql-socket-factory-connector-j-8` from 1.18.0 to 1.21.0

---
updated-dependencies:
- dependency-name: com.google.cloud.sql:postgres-socket-factory
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: com.google.cloud.sql:mysql-socket-factory-connector-j-8
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>

pom.xml

@@ -136,7 +136,7 @@
     <junit.version>4.13.2</junit.version>
     <mysql.version>8.4.0</mysql.version>
     <postgresql.version>42.7.4</postgresql.version>
-    <socket-factory.version>1.18.0</socket-factory.version>
+    <socket-factory.version>1.21.0</socket-factory.version>
   </properties>
 
   <dependencyManagement>