added shadowjar task

.github/workflows/shadowjar.yaml

+build-java-11:
+  runs-on: ubuntu-latest
+  steps:
+    - uses: actions/checkout@v3
+    - name: Set up JDK 11
+      uses: actions/setup-java@v3
+      with:
+        java-version: '11'
+        distribution: 'adopt'
+    - name: Validate Gradle wrapper
+      uses: gradle/wrapper-validation-action@e6e38bacfdf1a337459f332974bb2327a31aaf4b
+    - name: Build with Gradle
+      uses: gradle/gradle-build-action@67421db6bd0bf253fb4bd25b31ebb98943c375e1
+      with:
+        arguments: shadowjar
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