Upgrade Project Reactor 2020.0.13 -> 2020.0.18 (#51)

See:
- https://github.com/reactor/reactor/releases/tag/2020.0.14
- https://github.com/reactor/reactor/releases/tag/2020.0.15
- https://github.com/reactor/reactor/releases/tag/2020.0.16
- https://github.com/reactor/reactor/releases/tag/2020.0.17
- https://github.com/reactor/reactor/releases/tag/2020.0.18
- reactor/reactor@2020.0.13...2020.0.18

pom.xml

@@ -287,7 +287,7 @@
             <dependency>
                 <groupId>io.projectreactor</groupId>
                 <artifactId>reactor-bom</artifactId>
-                <version>2020.0.13</version>
+                <version>2020.0.18</version>
                 <type>pom</type>
                 <scope>import</scope>
             </dependency>