Bump mysql-connector-java from 8.0.17 to 8.0.18 in /modules/spo… (#1972)

Bumps [mysql-connector-java](https://github.com/mysql/mysql-connector-j) from 8.0.17 to 8.0.18.
- [Release notes](https://github.com/mysql/mysql-connector-j/releases)
- [Changelog](https://github.com/mysql/mysql-connector-j/blob/release/8.0/CHANGES)
- [Commits](https://github.com/mysql/mysql-connector-j/commits)

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

Co-authored-by: null <27856297+dependabot-preview[bot]@users.noreply.github.com>

Author: dependabot-preview[bot]

modules/spock/build.gradle

@@ -14,5 +14,5 @@ dependencies {
     testCompile 'org.apache.httpcomponents:httpclient:4.5.10'
 
     testRuntime 'org.postgresql:postgresql:42.2.8'
-    testRuntime 'mysql:mysql-connector-java:8.0.17'
+    testRuntime 'mysql:mysql-connector-java:8.0.18'
 }