update gh actions to java 21

.github/workflows/build.yml

@@ -6,6 +6,7 @@ name: Build
 on:
   push:
     paths-ignore:
+      - 'readmes/*'
       - '*.md'
   pull_request:
   workflow_dispatch:
@@ -15,18 +16,16 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v3
-    - name: Set up JDK 17
+    - name: Set up JDK 21
       uses: actions/setup-java@v2
       with:
-        java-version: 17
+        java-version: 21
         distribution: 'zulu'
     - name: Grant execute permission for gradlew
       run: chmod +x gradlew
 
     - name: Build with Gradle
       run: |
-        ./gradlew apiJar
-        ./gradlew remapApiJar
         ./gradlew build
     
     - name: Upload Artifact