Mirroring to public seems to fail more often than not lately

We are getting a newish error: 

```
remote: fatal: did not receive expected object 387a4da8425abcc7a15cd5884e3df8fc6e014184        
error: remote unpack failed: index-pack failed
To https://github.com/faster-cpython/benchmarking-public
 ! [remote rejected]   main -> main (failed)
```

Should look into a better way to do this -- it may be that the repo is now too large.