Bump io.projectreactor:reactor-core from 3.6.8 to 3.6.9

Bumps [io.projectreactor:reactor-core](https://github.com/reactor/reactor-core) from 3.6.8 to 3.6.9.
- [Release notes](https://github.com/reactor/reactor-core/releases)
- [Commits](reactor/reactor-core@v3.6.8...v3.6.9)

---
updated-dependencies:
- dependency-name: io.projectreactor:reactor-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

build.gradle

@@ -117,7 +117,7 @@ dependencies {
 
     testImplementation 'org.reactivestreams:reactive-streams-tck:' + reactiveStreamsVersion
     testImplementation "io.reactivex.rxjava2:rxjava:2.2.21"
-    testImplementation "io.projectreactor:reactor-core:3.6.8"
+    testImplementation "io.projectreactor:reactor-core:3.6.9"
 
     testImplementation 'org.testng:testng:7.10.2' // use for reactive streams test inheritance