downgrade spigot-api so it can compile with Java 8

Author: AoElite

build.gradle.kts

@@ -41,7 +41,7 @@ dependencies {
 
     implementation("org.jetbrains:annotations:24.1.0")
     compileOnly("org.geysermc.floodgate:api:2.0-SNAPSHOT")
-    compileOnly("org.spigotmc:spigot-api:1.20.6-R0.1-SNAPSHOT")
+    compileOnly("org.spigotmc:spigot-api:1.18.2-R0.1-SNAPSHOT")
     compileOnly("com.viaversion:viaversion-api:4.9.4-SNAPSHOT")
     //
     compileOnly("io.netty:netty-all:4.1.85.Final")