third_party: bump minecraft deps

Change-Id: Ib03669eef2f535ecf6711618b960f3058337fda5
diff --git a/WORKSPACE b/WORKSPACE
index 65298b1..f576986 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -212,7 +212,7 @@
 
 maven_install(
     artifacts = [
-        "org.spigotmc:spigot-api:1.15.2-R0.1-SNAPSHOT",
+        "org.spigotmc:spigot-api:1.15.2-R0.1-20200624.001023-124",
         "io.grpc:grpc-netty-shaded:1.29.0",
         "io.grpc:grpc-services:1.29.0",
     ] + IO_GRPC_GRPC_JAVA_ARTIFACTS,