add mcdr plugin packaging action

.github/workflows/package.yml

@@ -0,0 +1,43 @@
+name: CI for MCDR Plugin
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  package:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - name: Setup python
+      uses: actions/setup-python@v4
+      with:
+        python-version: 3.9
+
+    - uses: actions/cache@v3
+      with:
+        path: ~/.cache/pip
+        key: ${{ runner.os }}-pip-${{ hashFiles('**/requirements.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-
+
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install -r requirements.txt
+
+    - name: Pack Plugin
+      run: |
+        python -m mcdreforged pack -o ./package
+
+    - uses: actions/upload-artifact@v3
+      with:
+        name: Prime Backup distribution for ${{ github.sha }}
+        path: package/
+
+    - name: Publish distribution to release
+      if: github.event_name == 'push' && startsWith(github.ref, 'refs/tags/v')
+      uses: softprops/action-gh-release@v1
+      with:
+        files: package/*.mcdr