⚙️ :: (#2) Github publishing workflow 추가

.github/workflows/gradle.yml

@@ -0,0 +1,23 @@
+name: Publish package to the Maven Central Repository and GitHub Packages
+on:
+  release:
+    types: [created]
+jobs:
+  publish:
+    runs-on: ubuntu-latest 
+    permissions: 
+      contents: read
+      packages: write 
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Java
+        uses: actions/setup-java@v2
+        with:
+          java-version: '11'
+          distribution: 'adopt'
+      - name: Publish to the Maven Central Repository
+        run: gradle publish
+        env: 
+          MAVEN_USERNAME: ${{ secrets.OSSRH_USERNAME }}
+          MAVEN_PASSWORD: ${{ secrets.OSSRH_TOKEN }}
+          GITHUB_TOKEN: ${{ secrets.GH_TOKEN }}