Remove JAR manifest entries from Forge project as this is handled in the root build.gradle.

Forge/build.gradle

@@ -78,21 +78,6 @@ tasks.withType(JavaCompile) {
     source(project(":Common").sourceSets.main.allSource)
 }
 
-jar {
-
-    manifest {
-        attributes([
-                "Specification-Title"     : mod_name,
-                "Specification-Vendor"    : mod_author,
-                "Specification-Version"   : "1",
-                "Implementation-Title"    : project.name,
-                "Implementation-Version"  : project.jar.archiveVersion,
-                "Implementation-Vendor"   : mod_author,
-                "Implementation-Timestamp": new Date().format("yyyy-MM-dd'T'HH:mm:ssZ")
-        ])
-    }
-}
-
 jar.finalizedBy('reobfJar')
 
 publishing {