add retry script

.github/retry.sh

@@ -0,0 +1,22 @@
+#!/bin/bash
+# Execute command until exitcode is 0 or
+# maximum number of retries is reached
+# Example:
+#    ./retry <retries> <delay> <command>
+retries=$1
+delay=$2
+command="${@:3}"
+exitcode=0
+try=0
+until [ "$try" -ge $retries ]
+do
+  echo "$command"
+  eval "$command"
+  exitcode=$?
+  if [ $exitcode -eq 0 ]; then
+    break
+  fi
+  try=$((try+1))
+  sleep $2
+done
+exit $exitcode