Add retry action

Author: FelixHerrmann

.github/workflows/update.yml

@@ -13,5 +13,8 @@ jobs:
     - uses: actions/checkout@v2
     - name: Set name in local git-config
       run: git config --local user.name "runner"
-    - name: Run update script
-      run: swift update.swift ${{ secrets.GITHUB_TOKEN }}
+    - uses: nick-fields/retry@v2
+      with:
+        timeout_minutes: 5
+        max_attempts: 3
+        command: swift update.swift ${{ secrets.GITHUB_TOKEN }}