Fix ./gradlew usage

bootstrap/fabric/Jenkinsfile

@@ -1,7 +1,6 @@
 pipeline {
     agent any
     tools {
-        gradle 'Gradle'
         jdk 'Java 8'
     }
     options {
@@ -10,7 +9,7 @@ pipeline {
     stages {
         stage ('Build') {
             steps {
-                sh 'gradle clean build'
+                sh './gradlew clean build'
             }
             post {
                 success {

bootstrap/fabric/build.gradle

@@ -37,10 +37,6 @@ dependencies {
 repositories {
     mavenLocal()
 
-    maven {
-        url = uri('https://maven.fabricmc.net/')
-    }
-
     maven {
         url = uri('https://repo.nukkitx.com/maven-releases/')
     }