add preview builds

.github/workflows/preview-builds.yml

@@ -0,0 +1,64 @@
+name: Preview builds
+
+on:
+  push:
+    branches-ignore:
+      - master
+  pull_request:
+    paths:
+      - 'src/**'
+      - 'pom.xml'
+
+permissions:
+  pull-requests: write
+  contents: read
+
+jobs:
+  preview:
+    if: ${{ github.repository_owner == 'Slimefun' }}
+    name: Build and Publish the jar
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v3
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v3.11.0
+        with:
+          distribution: 'adopt'
+          java-version: '17'
+          java-package: jdk
+          architecture: x64
+
+      - name: Cache Maven packages
+        uses: actions/cache@v3
+        with:
+          path: ~/.m2
+          key: ${{ runner.os }}-m2-${{ hashFiles('**/pom.xml') }}
+          restore-keys: ${{ runner.os }}-m2
+
+      - name: Build with Maven
+        run: mvn package
+
+      - name: Upload to preview service
+        run: |
+          curl -X POST \
+            -H 'Authorization: ${{ secrets.PUBLISH_TOKEN }}' \
+            -H "X-Checksum: $(sha256sum 'target/Slimefun v4.9-UNOFFICIAL.jar')" \
+            --data-binary '@target/Slimefun v4.9-UNOFFICIAL.jar' \
+            https://preview-builds.walshy.dev/upload/Slimefun/${{ github.event.number }}/${{ github.run.number }}
+
+      - name: Post comment
+        uses: marocchino/sticky-pull-request-comment@v2
+        with:
+          message: |
+            #### Slimefun preview jar
+            This is the preview jar for this Pull Request.
+            This can be used for reviewers to test this PR.
+            
+            https://preview-builds.walshy.dev/download/Slimefun/${{ github.event.number }}/${{ github.run.number }}
+            
+            *Pusher: @${{ github.actor }}, Action: ${{ github.event_name }}*
+
+