Update dependency org.spigotmc:spigot-api to v1.20-R0.1-SNAPSHOT

Author: renovate[bot]

API/pom.xml

@@ -18,7 +18,7 @@
         <dependency>
             <groupId>org.spigotmc</groupId>
             <artifactId>spigot-api</artifactId>
-            <version>1.9.4-R0.1-SNAPSHOT</version>
+            <version>1.20-R0.1-SNAPSHOT</version>
             <scope>provided</scope>
         </dependency>
         <dependency>