Update workflow files

Author: lonefelidae16

.github/workflows/build.yml

@@ -12,7 +12,7 @@ jobs:
       matrix:
         # Use these Java versions
         java: [
-          17,    # Current Java LTS & minimum supported by Minecraft
+          21,    # Current Java LTS & minimum supported by Minecraft
         ]
         # and run on both Linux and Windows
         os: [ubuntu-20.04, windows-2022]
@@ -33,7 +33,7 @@ jobs:
         run: ./gradlew build
       - name: capture build artifacts
         if: ${{ runner.os == 'Linux' && matrix.java == '17' }} # Only upload artifacts built from latest java on one OS
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: Artifacts
           path: build/libs/