“Spring has sprung.” You’ll find that line used a lot this time of year. It’s catchy and cute, even though not very original. It is honest. Spring Training, at least the out-of-state variety, is complete. Right about now the A’s are taking the field for the first of three Bay Bridge Series games. The culmination of the series is in Oakland on Saturday. 1:05 start. But there’s also a special event on Sunday. Fan Appreciation Workout Day is this Sunday, April 6. Parking and admission are free to all fans. Here’s the skinny: