Bump io.projectreactor.kotlin:reactor-kotlin-extensions

Bumps [io.projectreactor.kotlin:reactor-kotlin-extensions](https://github.com/reactor/reactor-kotlin-extensions) from 1.1.5 to 1.2.3.
- [Release notes](https://github.com/reactor/reactor-kotlin-extensions/releases)
- [Commits](reactor/reactor-kotlin-extensions@v1.1.5...v1.2.3)

---
updated-dependencies:
- dependency-name: io.projectreactor.kotlin:reactor-kotlin-extensions
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

kotlin-self-executable-jar/kotlin-spring-executable/pom.xml

@@ -30,7 +30,7 @@
         <dependency>
             <groupId>io.projectreactor.kotlin</groupId>
             <artifactId>reactor-kotlin-extensions</artifactId>
-            <version>1.1.5</version>
+            <version>1.2.3</version>
         </dependency>
         <!-- Kotlin Reflect -->
         <dependency>