Bump influxdb-java from 2.20 to 2.21 in /modules/influxdb (#3568)

Bumps [influxdb-java](https://github.com/influxdata/influxdb-java) from 2.20 to 2.21.
- [Release notes](https://github.com/influxdata/influxdb-java/releases)
- [Changelog](https://github.com/influxdata/influxdb-java/blob/master/CHANGELOG.md)
- [Commits](influxdata/influxdb-java@influxdb-java-2.20...influxdb-java-2.21)

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

modules/influxdb/build.gradle

@@ -3,6 +3,6 @@ description = "Testcontainers :: InfluxDB"
 dependencies {
     compile project(':testcontainers')
 
-    compileOnly 'org.influxdb:influxdb-java:2.20'
-    testCompile 'org.influxdb:influxdb-java:2.19'
+    compileOnly 'org.influxdb:influxdb-java:2.21'
+    testCompile 'org.influxdb:influxdb-java:2.21'
 }